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Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2017	Mar. 07, 2018	Jun. 30, 2017
Document Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY
Trading Symbol	NK
Entity Registrant Name	NANTKWEST, INC.
Entity Central Index Key	0001326110
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		79,031,520
Entity Public Float			$ 208.3

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 23,872	$ 8,083
Due from related parties	154	1,089
Prepaid expenses and other current assets	4,152	5,135
Marketable securities	104,280	190,838
Total current assets	132,458	205,145
Marketable securities, noncurrent	29,600	87,571
Property, plant and equipment, net	76,726	18,906
Cost method investment	8,500	0
Intangible assets, net	2,826	5,086
Other assets	330	788
Total assets	250,440	317,496
Current liabilities:
Accounts payable	5,865	4,045
Accrued expenses	11,267	5,864
Due to related parties	2,363	1,753
Other current liabilities	1,373	891
Total current liabilities	20,868	12,553
Build-to-suit liability, less current portion	4,909	5,651
Financing obligation, less current portion	1,741	2,025
Deferred rent	3,325	2,426
Deferred revenue	166	187
Deferred tax liability	498	996
Other liabilities	89	240
Total liabilities	31,596	24,078
Commitments and contingencies (Note 8)
Stockholders’ equity
Common stock	8	8
Additional paid-in capital	717,930	680,757
Accumulated other comprehensive loss	(381)	(284)
Accumulated deficit	(498,713)	(387,063)
Total stockholders’ equity	218,844	293,418
Total liabilities and stockholders’ equity	$ 250,440	$ 317,496

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016	Jul. 31, 2015	Jun. 30, 2015
Statement Of Financial Position [Abstract]
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	500,000,000	500,000,000		100,000,000
Common stock, shares issued	79,021,878	81,983,937	9,531,200
Common stock, shares outstanding	79,021,878	81,983,937

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Revenue	$ 45	$ 44	$ 236
Operating expenses:
Research and development	42,044	29,153	11,434
Selling, general and administrative	57,121	95,391	227,678
Total operating expenses	99,165	124,544	239,112
Loss from operations	(99,120)	(124,500)	(238,876)
Other income (expense):
Investment income, net	2,665	3,097	2,988
Change in fair value of warrant liability	0	0	(1,366)
Interest expense	(618)	(66)	0
Other income, net	157	88	77
Total other income	2,204	3,119	1,699
Loss before income taxes	(96,916)	(121,381)	(237,177)
Income tax benefit, net	(493)	(572)	(301)
Net loss	$ (96,423)	$ (120,809)	$ (236,876)
Net loss per share:
Basic and diluted	$ (1.20)	$ (1.47)	$ (3.31)
Weighted average number of shares during the period:
Basic and diluted	80,583,910	81,979,005	71,519,609

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (96,423)	$ (120,809)	$ (236,876)
Other comprehensive loss, net of income taxes:
Net unrealized gain (loss) on available-for-sale securities	(65)	5	(192)
Reclassification of net realized gains on available-for-sale securities included in net loss	(32)	(97)	0
Total other comprehensive loss	(97)	(92)	(192)
Comprehensive loss	$ (96,520)	$ (120,901)	$ (237,068)

Consolidated Statements of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Initial Public Offering	Private Placement	Brink Biologics Inc Spinout	Common Class A	Common Class A Initial Public Offering	Common Class A Private Placement	Common Class A Brink Biologics Inc Spinout	Common Stock	Common Stock Initial Public Offering	Common Stock Private Placement	Common Stock Brink Biologics Inc Spinout	Additional Paid-in Capital	Additional Paid-in Capital Initial Public Offering	Additional Paid-in Capital Private Placement	Additional Paid-in Capital Brink Biologics Inc Spinout	Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) Initial Public Offering	Accumulated Other Comprehensive Income (Loss) Private Placement	Accumulated Other Comprehensive Income (Loss) Brink Biologics Inc Spinout	Accumulated Deficit	Accumulated Deficit Initial Public Offering	Accumulated Deficit Private Placement	Accumulated Deficit Brink Biologics Inc Spinout
Beginning Balance at Dec. 31, 2014	$ 57,591				$ 6				$ 0				$ 71,158				$ 0				$ (13,573)
Beginning Balance, Shares at Dec. 31, 2014					61,094,367				0
Exercise of stock options	878				$ 1				$ 0				877				0				0
Exercise of stock options, Shares					949,396				177,703
Stock-based compensation expense	211,221				$ 0				$ 0				211,221				0				0
Vesting of restricted stock units (RSUs)					0				485,150
Net share settlement for RSU vesting and option exercises	(2,415)				$ 0				$ 0				(2,415)				0				0
Net share settlement for RSU vesting and option exercises, Shares					0				(96,612)
Warrants issued in conjunction with Inex Bio purchase	5,170				$ 0				$ 0				5,170				0				0
Exercise of warrants	7,348				$ 0				$ 0				7,348				0				0
Exercise of warrants, Shares					4,106,492				570,609
Repurchase of common stock	$ (4,798)				$ 0				$ 0				(4,798)				0				0
Repurchase of common stock, Shares	0				(249,952)				0
Reclassification of warrant liability due to exercise	$ 1,543				$ 0				$ 0				1,543				0				0
Conversion to Class A common stock	0				$ (7)				$ 7				0				0				0
Conversion to Class A common stock, Shares					(65,900,303)				65,900,303
Issuance of common stock less issuance costs	77,977	$ 221,475	$ 17,000		$ 0	$ 0	$ 0		$ 0	$ 1	$ 0		77,977	$ 221,474	$ 17,000		0	$ 0	$ 0		0	$ 0	$ 0
Issuance of common stock less issuance costs, Shares					0	0	0		4,063,333	9,531,200	680,000
Stockholders Equity Note Spinoff Transaction				$ 73				$ 0				$ 0				$ 0				$ 0				$ 73
Other comprehensive loss	(192)				$ 0				$ 0				0				(192)				0
Net loss	(236,876)				0				0				0				0				(236,876)
Ending Balance at Dec. 31, 2015	355,995				$ 0				$ 8				606,555				(192)				(250,376)
Ending Balance, Shares at Dec. 31, 2015					0				81,311,686
Exercise of stock options	1,373				$ 0				$ 0				1,373				0				0
Exercise of stock options, Shares					0				2,398,883
Stock-based compensation expense	73,852				$ 0				$ 0				73,852				0				0
Vesting of restricted stock units (RSUs)					0				537,982
Net share settlement for RSU vesting and option exercises	(1,106)												(1,106)				0				0
Net share settlement for RSU vesting and option exercises, Shares					0				(154,127)
Exercise of warrants	52				$ 0				$ 0				52				0				0
Exercise of warrants, Shares					0				47,457
Change in accounting principle - ASU 2016-09 forfeiture	0				$ 0				$ 0				31				0				(31)
Repurchase of common stock	$ (15,847)				$ 0				$ 0				0				0				(15,847)
Repurchase of common stock, Shares	(2,157,944)				0				(2,157,944)
Other comprehensive loss	$ (92)				$ 0				$ 0				0				(92)				0
Net loss	(120,809)				0				0				0				0				(120,809)
Ending Balance at Dec. 31, 2016	$ 293,418				$ 0				$ 8				680,757				(284)				(387,063)
Ending Balance, Shares at Dec. 31, 2016	81,983,937				0				81,983,937
Exercise of stock options	$ 1,154				$ 0				$ 0				1,154				0				0
Exercise of stock options, Shares					0				614,136
Stock-based compensation expense	36,997				$ 0				$ 0				36,997				0				0
Vesting of restricted stock units (RSUs)					0				244,209
Net share settlement for RSU vesting and option exercises	(1,039)												(1,039)				0				0
Net share settlement for RSU vesting and option exercises, Shares					0				(234,020)
Exercise of warrants	61				$ 0				$ 0				61				0				0
Exercise of warrants, Shares					0				47,226
Repurchase of common stock	$ (15,227)				$ 0				$ 0				0				0				(15,227)
Repurchase of common stock, Shares	(3,633,610)				0				(3,633,610)
Other comprehensive loss	$ (97)				$ 0				$ 0				0				(97)				0
Net loss	(96,423)				0				0				0				0				(96,423)
Ending Balance at Dec. 31, 2017	$ 218,844				$ 0				$ 8				$ 717,930				$ (381)				$ (498,713)
Ending Balance, Shares at Dec. 31, 2017	79,021,878				0				79,021,878

Consolidated Statements of Stockholders' Equity (Deficit) (Parenthetical)	12 Months Ended
	Dec. 31, 2015 USD ($)
Stock issuance costs	$ 28,000
Initial Public Offering
Stock issuance costs	$ 16,800,000

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities:
Net loss	$ (96,423)	$ (120,809)	$ (236,876)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	5,566	3,607	1,472
Stock-based compensation expense	36,997	73,852	211,221
Amortization of net premiums on marketable securities	1,597	2,182	38
Deferred income tax benefit	(497)	(575)	(302)
Non-cash interest items, net	720	(573)	72
Loss on disposal of assets	64	18	0
Gain on sales of marketable securities	(32)	(137)	(2,501)
Change in value of warrant liability	0	0	1,366
Loss incurred by Inex Bio	0	0	56
Gain on settlement of note payable	0	0	(133)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	156	(1,458)	(3,231)
Other assets	458	153	(1,194)
Accounts payable	150	888	627
Accrued expenses and other liabilities	(299)	2,127	1,991
Due to related parties	1,562	378	1,352
Deferred rent and revenue	1,201	1,754	737
Net cash used in operating activities	(48,780)	(38,593)	(25,305)
Investing activities:
Purchases of property, plant and equipment	(34,815)	(6,560)	(2,241)
Purchase of cost method investment	(8,500)	0	0
Purchases of marketable securities	(111,355)	(272,999)	(198,068)
Sales/maturities of marketable securities	254,222	165,887	26,903
Purchase of Inex Bio Inc., net of cash acquired	0	0	(1,818)
Net cash (used in) provided by investing activities	99,552	(113,672)	(175,224)
Financing activities:
Principal payments of financing/capital lease obligations	(19,932)	(32)	0
Repurchase of common stock	(15,227)	(15,847)	(4,798)
Proceeds from exercise of stock options	1,154	1,373	878
Proceeds from exercise of warrants	61	52	7,348
Net share settlement for RSU vesting and option exercises	(1,039)	(1,106)	(2,415)
Proceeds from equity offerings, net of issuance costs	0	0	316,452
Repayments of notes payable	0	0	(132)
Net cash (used in) provided by financing activities	(34,983)	(15,560)	317,333
Net increase (decrease) in cash and cash equivalents	15,789	(167,825)	116,804
Cash and cash equivalents, beginning of period	8,083	175,908	59,104
Cash and cash equivalents, end of period	23,872	8,083	175,908
Cash paid during the period for:
Interest	668	66	0
Income taxes	3	2	1
Supplemental disclosure of non-cash investing and financing activities:
Property and equipment purchases acquired under capital lease	19,448	0	0
Property and equipment purchases included in accounts payable, accrued expenses, and other liabilities	9,500	2,753	457
Unrealized loss on marketable securities	(97)	(102)	(182)
Cashless exercise of stock options and warrants	16	456	1,543
Estimated fair value of buildings under build-to-suit leases	0	5,139	2,740
Lease incentive with a related party	0	849	0
Inex Bio Inc
Supplemental disclosure of non-cash investing and financing activities:
Issuance of warrants in Inex Bio, Inc. acquisition	$ 0	$ 0	$ 5,170

Description of Business and Basis of Presentation	12 Months Ended
Description of Business and Basis of Presentation	Dec. 31, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Description of Business and Basis of Presentation	1. Description of Business and Basis of Presentation Organization NantKwest, Inc. (the Company) was incorporated in Illinois on October 7, 2002 under the name ZelleRx Corporation. On January 22, 2010, the Company changed its name to Conkwest, Inc., and on July 10, 2015, the Company changed its name to NantKwest, Inc. In March 2014, the Company redomesticated from the State of Illinois to the State of Delaware and the Illinois Company ceased to exist. The Company is a pioneering clinical-stage immunotherapy biotechnology company headquartered in San Diego, California with certain operations in Culver City and El Segundo, California and Woburn, Massachusetts. The Company is focused on harnessing the power of the innate immune system by using the natural killer cell to treat cancer, infectious diseases and inflammatory diseases. A critical aspect of our strategy is to invest significantly in expanding our aNK platform and the development of our product candidates. The Company holds the exclusive right to commercialize activated natural killer (aNK) cells, a commercially viable natural killer cell-line, and a variety of genetically modified derivatives capable of killing cancer and virally infected cells. The Company owns corresponding U.S. and foreign composition and methods-of-use patents and applications covering the clinical use of aNK cells as a therapeutic to treat a spectrum of clinical conditions. The Company also licensed exclusive commercial rights to a portfolio of CD16 bearing aNK cells along with the corresponding U.S. and foreign composition and methods-of-use patents and applications covering the non-clinical use in laboratory testing of monoclonal antibodies, as well as clinical use as a therapeutic to treat cancers in combination with antibody products. The Company has licensed or sub-licensed its CD16 bearing aNK cell lines and intellectual property to numerous pharmaceutical and biotechnology companies for such non-clinical uses. The Company also licensed exclusive commercial rights to a unique HER2-specific receptor bearing aNK cell line along with the corresponding U.S. and foreign composition and methods-of-use patents and applications covering clinical use as a therapeutic to treat cancers. The Company retains exclusive worldwide rights to clinical and research data, intellectual property and know-how developed with the Company’s aNK cells, as well as the only clinical grade master cell bank. Initial Public Offering In July 2015, the Company completed an initial public offering (IPO) of its common stock. In connection with its IPO, the Company issued and sold 9,531,200 shares of its common stock, at a price to the public of $25 per share. The Company’s shares of common stock began trading on the NASDAQ Global Market on July 28, 2015. As a result of the IPO, the Company received approximately $221.5 million in net proceeds, after deducting underwriting discounts, commissions and offering expenses of $16.8 million. Liquidity As of December 31, 2017, the Company had an accumulated deficit of approximately $498.7 million. The Company also had negative cash flow from operations of approximately $48.8 million during the year ended December 31, 2017. The Company expects that it will likely need additional capital to further fund development of, and seek regulatory approvals for, its product candidates, and begin to commercialize any approved products. The Company is currently focused primarily on the development of immunotherapeutic treatments for cancers and debilitating viral infections using targeted cancer killing cell lines, and believes such activities will result in the Company’s continued incurrence of significant research and development and other expenses related to those programs. If the clinical trials for any of the Company’s product candidates fail or produce unsuccessful results and those product candidates do not gain regulatory approval, or if any of the Company’s product candidates, if approved, fails to achieve market acceptance, the Company may never become profitable. Even if the Company achieves profitability in the future, it may not be able to sustain profitability in subsequent periods. The Company intends to cover its future operating expenses through cash and cash equivalents, marketable securities, and through a combination of equity offerings, debt financings, government or other third-party funding, marketing and distribution arrangements and other collaborations, strategic alliances and licensing arrangements. Additional financing may not be available to the Company when needed and, if available, financing may not be obtained on terms favorable to the Company or its stockholders. While the Company expects its existing cash and cash equivalents and marketable securities will enable it to fund operations and capital expenditure requirements for the next twelve months, it may not have sufficient funds to reach commercialization. Failure to obtain adequate financing when needed may require the Company to delay, reduce, limit or terminate some or all of its development programs or future commercialization efforts or grant rights to develop and market product candidates that the Company might otherwise prefer to develop and market itself, which could adversely affect the Company’s ability to operate as a going concern. If the Company raises additional funds from the issuance of equity securities, substantial dilution to existing stockholders may result. If the Company raises additional funds by incurring debt financing, the terms of the debt may involve significant cash payment obligations, as well as covenants and specific financial ratios that may restrict the Company’s ability to operate its business. Forward Stock Split On July 10, 2015, the Company effected a 1.8515-for-1 forward stock split of its outstanding common stock. All applicable share data, per share amounts and related information on the consolidated financial statements and notes thereto have been adjusted retroactively to give effect to the 1.8515-for-1 forward stock split. See Note 11 for further information.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Principles of Consolidation and Equity Investments

The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries, and have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP). All intercompany amounts have been eliminated.

The Company applies the variable interest model under Accounting Standards Codification (ASC) Topic 810, Consolidation, to any entity in which the Company holds an equity investment or to which the Company has the power to direct the entity's most significant economic activities and the ability to participate in the entity's economics. If the entity is within the scope of the variable interest model and meets the definition of a variable interest entity (VIE), the Company considers whether it must consolidate the VIE or provide additional disclosures regarding the Company's involvement with the VIE. If the Company determines that it is the primary beneficiary of the VIE, the Company will consolidate the VIE. This analysis is performed at the initial investment in the entity or upon any reconsideration event.

For entities the Company holds as an equity investment and are not consolidated under the VIE Model, the Company considers whether its investment constitutes ownership of a majority of the voting interests in the entity and therefore should be considered for consolidation under the voting interest model.

Unconsolidated equity investments in the common stock or in-substance common stock of an entity under which the Company is able to exercise significant influence, but not control, are accounted for using the equity method. The Company’s ability to exercise significant influence is generally indicated by ownership of 20 to 50 percent interest in the voting securities of the entity.

Use of Estimates

The preparation of consolidated financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make certain estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. On an ongoing basis, the Company evaluates its estimates, including those related to the valuation of warrants, stock-based compensation, the valuation allowance for deferred tax assets, preclinical and clinical trial accruals, impairment assessments, and the valuation of build-to-suit lease assets. The Company bases its estimates on historical experience and on various other market-specific and relevant assumptions that it believes to be reasonable under the circumstances. Actual results could differ from those estimates.

Risks and Uncertainties

Contingencies

The Company records accruals for loss contingencies to the extent that the Company concludes it is probable that a liability has been incurred and the amount of the related loss can be reasonably estimated. The Company evaluates, on a quarterly basis, developments in legal proceedings and other matters that could cause a change in the potential amount of the liability recorded or of the range of potential losses disclosed. Additionally, the Company has reflected its right to insurance recoveries, limited to the extent of incurred or probable losses, as a receivable when such recoveries have been agreed to with its third-party insurers and receipt is deemed probable. This includes instances where the Company’s third-party insurers have agreed to pay certain legal defense costs directly to applicable law firms on the Company’s behalf.

Cash, Cash Equivalents and Marketable Securities

The Company invests its excess funds in investment grade short- to intermediate-term corporate debt securities, commercial paper, government sponsored securities and foreign government bonds and classifies these investments as available-for-sale. The Company considers all highly liquid investments purchased with original maturities of three months or less to be cash equivalents and all investments purchased with original maturities of greater than three months as marketable securities. Marketable securities with original maturities of 12 months or less are classified as short-term and marketable securities with original maturities greater than 12 months are classified as long-term. All marketable securities are reported at fair value and any unrealized gains and losses are reported as a component of accumulated other comprehensive income (loss), net of tax, on the consolidated statement of stockholders’ equity (deficit), with the exception of unrealized losses believed to be other-than-temporary, which are recorded within other income (expense) in the current period. Realized gains and losses are included in other income (expense) on the consolidated statements of operations. Realized gains and losses from the sale of the securities and the amounts, net of tax, reclassified out of accumulated other comprehensive income, if any, are determined on a specific identification basis.

The Company periodically evaluates whether declines in fair values of its investments below their book value are other-than-temporary. This evaluation consists of several qualitative and quantitative factors regarding the severity and duration of the unrealized loss, as well as the Company’s ability and intent to hold the investment until a forecasted recovery occurs. Additionally, the Company assesses whether it has plans to sell the security or it is more likely than not it will be required to sell any investment before recovery of its amortized cost basis. Factors considered include quoted market prices, recent financial results and operating trends, implied values from any recent transactions or offers of investee securities, credit quality of debt instrument issuers, other publicly available information that may affect the value of our investments, duration and severity of the decline in value and the Company’s strategy and intentions for holding the investment. There were no other than temporary impairments recorded in years ended December 31, 2017, 2016 and 2015.

The Company minimizes its credit risk associated with cash and cash equivalents by periodically evaluating the credit quality of its primary financial institutions. While the Company maintains cash deposits in FDIC insured financial institutions in excess of federally insured limits, management believes the Company is not exposed to significant credit risk due to the financial position of the depository institutions in which those deposits are held. The Company has not experienced any losses on such accounts.

The Company has funded a certificate of deposit (CD) as a substitute letter of credit for one of the leased properties. This CD is reported as long-term restricted cash and is included in other assets on the consolidated balance sheet as the landlord is the beneficiary of the account and the Company is not able to access the funds during the term of the lease.

Property, Plant and Equipment

Property, plant and equipment is stated at historical cost less accumulated depreciation. Historical cost includes expenditures that are directly attributable to the acquisition of the items. All repairs and maintenance are charged to net loss during the financial period in which they are incurred. Depreciation of property, plant and equipment is calculated using the straight-line method over the estimated useful lives of the assets, as follows:

Buildings		39 years
Software		3 years
Laboratory equipment		5 years
Furniture & fixtures		5 years
IT equipment		3 years
Leasehold improvements		The lesser of the lease term or the life of the asset

On disposal or impairment of property, plant and equipment, the cost and related accumulated depreciation is removed from the consolidated financial statements and the net amount, less any proceeds, is included in other income / (loss) on the consolidated statement of operations.

The Company is deemed to be the owner, for accounting purposes, during the construction phase of certain long-lived assets under build-to-suit lease arrangements because of its involvement with the construction, its exposure to any potential cost overruns and its other commitments under the arrangements. In these cases, the Company recognizes a build-to-suit lease asset under construction and a corresponding build-to-suit lease liability on the consolidated balance sheets.

Upon completion of construction, the Company evaluates the de-recognition of the asset and liability under the provisions of ASC 840-40 Leases – Sales-Leaseback Transactions. Where the lease does not meet the criteria for sale-leaseback accounting treatment, due to the continuing involvement in the project resulting from the significant collateral we provided to the landlord in the form of building improvements, the Company accounts for the lease as a financing obligation. Under the financing obligation, the deemed value of the building is capitalized as property, plant and equipment with an offsetting financing obligation on the consolidated balance sheets. The asset is then depreciated over the building’s estimated useful life. At the end of the lease term, the Company will de-recognize both the net book values of the building and financing obligation.

Cost Method Investment

The Company owns non-marketable equity securities that are accounted for under the cost method because the preferred stock is not considered in-substance common stock and the preferred stock does not have a readily determinable fair value. All investments are reviewed on a regular basis for possible impairment. If an investment's fair value is determined to be less than its net carrying value and the decline is determined to be other-than-temporary, the investment is written down to its fair value. Such an evaluation is judgmental and dependent on specific facts and circumstances. Factors considered in determining whether an other-than-temporary decline in value has occurred include: market value of the investment based on most recent rounds of financing by the investee, length of time that the market value was below its cost basis, financial condition and business prospects of the investee, the Company’s intent and ability to retain the investment for a sufficient period of time to allow for recovery in market value of the investment, issues that raise concerns about the investee's ability to continue as a going concern, and any other information that the Company may be aware of related to the investment.

Intangible Assets

Intangible assets consist of the cost of reacquiring a technology license in the asset purchase of Inex Bio. The Company calculates amortization expense for acquired technology licenses using the straight-line method over the estimated useful lives, which is 4 years.

Patents

The Company expenses patent costs, including related legal costs, as incurred and records such costs within general and administrative expenses on the consolidated statements of operations.

Impairments

The Company’s long-lived assets include property, plant and equipment and intangible assets. The Company reviews long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability is measured by comparison of the carrying amount to the future net cash flows that the assets are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the assets exceeds the projected undiscounted future cash flows arising from the asset using a discount rate determined by management to be commensurate with the risk inherent to the Company’s current business model. There were no impairment losses recognized during the years ended December 31, 2017, 2016 and 2015.

Fair Value of Financial Instruments

The accounting standard for fair value measurements provides a framework for measuring fair value and requires disclosures regarding fair value measurements. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date, based on the Company’s principal or, in absence of a principal, most advantageous market for the specific asset or liability.

The Company uses a three-tier fair value hierarchy to classify and disclose all assets and liabilities measured at fair value on a recurring basis, as well as assets and liabilities measured at fair value on a non-recurring basis, in periods subsequent to their initial measurement. The hierarchy requires the Company to use observable inputs when available, and to minimize the use of unobservable inputs, when determining fair value.

The three tiers are defined as follows:

•

Level 1—Observable inputs that reflect quoted market prices (unadjusted) for identical assets or liabilities in active markets at the measurement date. Since valuations are based on quoted prices that are readily and regularly available in an active market, valuation of these products does not entail a significant degree of judgment. The Company’s Level 1 assets consist of bank deposits and money market funds.

•

Level 2—Observable inputs other than quoted prices in active markets that are observable either directly or indirectly in the marketplace for identical or similar assets and liabilities. The Company’s Level 2 assets consist of corporate debt securities including commercial paper, government sponsored securities and corporate bonds, as well as foreign municipal securities.

•

Level 3— Valuations based on inputs that are unobservable and significant to the overall fair value measurement.

During the years ended December 31, 2017, 2016 and 2015, no transfers were made into or out of the Level 1, 2 or 3 categories. The Company will continue to review the fair value inputs on a quarterly basis.

The Company utilizes a third-party pricing service to assist in obtaining fair value pricing for investments. Inputs are documented in accordance with the fair value disclosure hierarchy.

Until the second quarter of 2015, we had common stock warrants that met the definition of derivative financial instruments and were accounted for as a derivative liability. The fair value of this warrant derivative liability was based on a Monte Carlo simulation model at each reporting period. Estimating the fair value of the underlying shares was highly complex and subjective because our stock was not publicly traded at the time. The derivative warrant liability was settled upon the exercise of the underlying warrants in the second quarter of 2015.

Preclinical and Clinical Trial Accruals

As part of the process of preparing the financial statements, the Company is required to estimate expenses resulting from obligations under contracts with vendors, clinical research organizations and consultants. The financial terms of these contracts vary and may result in payment flows that do not match the periods over which materials or services are provided under such contracts.

The Company estimates clinical trial and research agreement related expenses based on the services performed, pursuant to contracts with research institutions and clinical research organizations and other vendors that conduct clinical trials and research on the Company’s behalf. In accruing clinical and research related fees, the Company estimates the time period over which services will be performed and activity expended in each period. If the actual timing of the performance of services or the level of effort varies from the estimate, the Company will adjust the accrual accordingly. Payments made to third parties under these arrangements in advance of the receipt of the related services are recorded as prepaid expenses until the services are rendered.

Transactions with Related Parties

As outlined in Note 9, the Company has various agreements with different related parties. Some are billed and settled in cash monthly. Others are billed quarterly and settled in cash the following month. Monthly accruals are made for all quarterly billing arrangements.

Lease Obligations

The Company categorizes leases at their inception as either operating or capital leases. On certain lease agreements, the Company may receive rent holidays and other incentives. The Company recognizes lease costs on a straight-line basis without regard to deferred payment terms, such as rent holidays that defer the commencement date of required payments. Additionally, incentives the Company receives for leases categorized as operating leases are treated as a reduction of cost over the term of the agreement.

The Company establishes assets and liabilities for the estimated construction costs incurred under build-to-suit lease arrangements to the extent the Company is involved in the construction of structural improvements or takes construction risk prior to commencement of a lease. Upon occupancy of facilities under build-to-suit leases, the Company assesses whether these arrangements qualify for sales recognition under the sale-leaseback accounting guidance. If the Company continues to be the deemed owner, the facilities are accounted for as financing leases.

Income Taxes

The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the financial reporting and tax basis of assets and liabilities, as well as for operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using the tax rates that are expected to apply to taxable income for the years in which those tax assets and liabilities are expected to be realized or settled. The Company records valuation allowances to reduce deferred tax assets to the amount the Company believes is more likely than not to be realized.

The Company recognizes uncertain tax positions when the positions will be more likely than not upheld on examination by the taxing authorities based solely upon the technical merits of the positions. The Company recognizes interest and penalties, if any, related to unrecognized income tax uncertainties in income tax expense. The Company did not have any accrued interest or penalties associated with uncertain tax positions as of December 31, 2017 and 2016.

The Company is subject to U.S. federal income tax, as well as income tax in Korea, California and other states. The federal returns for tax years 2014 through 2017 remain open to examination; the California returns remain subject to examination for tax years 2013 through 2017. Carryforward attributes that were generated in years where the statute of limitations is closed may still be adjusted upon examination by the Internal Revenue Service or other respective tax authority. All other state jurisdictions remain open to examination. No income tax returns are currently under examination by taxing authorities.

Stock Repurchases

In November 2015, the board of directors approved a share repurchase program (2015 Share Repurchase Program) allowing the CEO or CFO, on behalf of the Company, to repurchase from time to time, in the open market or in privately negotiated transactions, up to $50.0 million of the Company’s outstanding shares of common stock, exclusive of any commissions, markups or expenses. The timing and amounts of any purchases will be based on market conditions and other factors, including price, regulatory requirements and other corporate considerations. The 2015 Share Repurchase Program does not require the purchase of any minimum number of shares and may be suspended, modified or discontinued at any time without prior notice. The Company expects to finance the purchases with existing cash balances. As it is the intent for the repurchased shares to be retired, the Company has elected to account for the shares repurchased under the constructive retirement method. For shares repurchased in excess of par, the Company will allocate the excess value to accumulated deficit.

Revenue Recognition and Deferred Revenue

The Company derives substantially all of its revenue from non-exclusive license agreements with numerous pharmaceutical and biotechnology companies granting them the right to use the Company’s cell lines and intellectual property for non-clinical use. These license agreements generally include nonrefundable upfront fees and annual research license fees for such use, as well as commercial fees for sales of the licensees’ products developed or manufactured using the Company’s intellectual property and cell lines. The Company’s license agreements also may include milestone payments, although to date, the Company has not generated any revenue from milestone payments. The Company recognizes revenue when (i) persuasive evidence of an arrangement exists; (ii) delivery of the products and/or services has occurred; (iii) the fees are fixed or determinable; and (iv) collectability is reasonably assured.

When entering into an arrangement, the Company first determines whether the arrangement includes multiple deliverables and is subject to accounting guidance in Accounting Standards Codification (ASC) Subtopic 605-25, Multiple-Element Arrangements. If the Company determines that an arrangement includes multiple elements, it determines whether the arrangement should be divided into separate units of accounting and how the arrangement consideration should be measured and allocated among the separate units of accounting.

An element qualifies as a separate unit of accounting when the delivered element has standalone value to the customer. The Company’s agreements do not include a general right of return relative to delivered elements. Any delivered elements that do not qualify as separate units of accounting are combined with other undelivered elements within the arrangement as a single unit of accounting. If the arrangement constitutes a single combined unit of accounting, the Company determines the revenue recognition method for the combined unit of accounting and recognizes the revenue over the period from inception through the date the last deliverable within the single unit of accounting is delivered.

License rights and non-contingent deliverables, such as knowledge transfer, do not have standalone value as they are not sold separately and they cannot be resold and, consequently are considered a single unit of accounting. Therefore, license revenue in the form of upfront payments is deferred and recognized over the applicable period of the Company’s substantive performance obligations or the period the rights granted are in effect.

The Company recognizes a milestone payment when earned if it is substantive and the Company has no ongoing performance obligations related to the milestone. A milestone payment is considered substantive if it 1) is commensurate with either the Company’s performance to achieve the milestone or the enhanced value of the delivered item as a result of a specific outcome resulting from the Company’s performance to achieve the milestone; 2) relates solely to past performance; and 3) is reasonable relative to all of the deliverables and payment terms, including other potential milestone consideration within the arrangement.

The Company records any amounts received prior to satisfying the revenue recognition criteria as deferred revenue on the accompanying consolidated balance sheets.

Research and Development Costs

Major components of research and development costs include cash compensation, stock-based compensation, depreciation and amortization expense on research and development property and equipment and intangible assets, costs of preclinical studies, clinical trials and related clinical manufacturing, costs of drug development, costs of materials and supplies, facilities cost, overhead costs, regulatory and compliance costs, and fees paid to consultants and other entities that conduct certain research and development activities on the Company’s behalf. Costs incurred in research and development are expensed as incurred.

Stock-Based Compensation

The Company accounts for stock-based compensation expense related to stock options granted to employees and members of its board of directors by estimating the fair value of each stock option on the date of grant using the Black-Scholes options-pricing model. For awards subject to service-based vesting conditions, stock-based compensation expense is recognized over the vesting period using the straight-line method. The fair value of restricted stock units is determined by the closing market price of the Company’s common stock on the date of grant and is also recognized over the vesting period using the straight-line method.

For performance-based awards to employees (i) the fair value of the award is determined on the grant date, (ii) the Company assesses the probability of the individual milestones under the award being achieved, and (iii) the fair value of the shares subject to the milestone is expensed over the service period commencing once management believes the performance criteria is probable of being met.

The Company also accounts for equity instruments issued to non-employees using a fair value approach under ASC Subtopic 505-50, Equity-Based Payments to Non-Employees. The Company adjusts the values of the restricted stock units and stock options granted based on the underlying Company stock price at the end of each quarter. Stock options adjustments are made via the Black-Scholes option-pricing model. The adjusted value of non-employee stock-based compensation is recognized as an expense over the period over which services are received.

In the third quarter of 2017, the Company implemented Financial Accounting Standards Board (FASB) issued Accounting Standard Update 2017-09 (ASU 2017-09) Stock Compensation (Topic 718): Scope of Modification Accounting. This guidance determines which changes to the terms and conditions of share-based payment awards require an entity to apply modification accounting. The adoption of this guidance had no impact to our consolidated financial statements.

In the second quarter of 2016, the Company implemented FASB ASU 2016-09, Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. Therefore, the Company is accounting for share-based award forfeitures only as they occur rather than applying an estimated forfeiture rate.

Litigation Costs

We expense legal fees as they are incurred.

Comprehensive Loss

Comprehensive loss is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources. Comprehensive loss is composed of net loss and other comprehensive loss. The Company's other comprehensive loss consists of unrealized gains and losses on marketable securities classified as available-for-sale.

Basic and Diluted Net Loss per Share of Common Stock

Basic net loss per share is calculated by dividing the net loss by the weighted-average number of common shares outstanding for the period. Diluted loss per share is computed similarly to basic loss per share except that the denominator is increased to include the number of additional shares that would have been outstanding if the potential common shares had been issued and if the additional common shares were dilutive.

For all periods presented, potentially dilutive securities are excluded from the computation of fully diluted loss per share as their effect is anti-dilutive. The following table details those securities that have been excluded from the computation of potentially dilutive securities:

	As of December 31,
	2017		2016		2015
Outstanding options		5,693,250		6,307,386		8,777,893
Outstanding restricted stock units		888,189		814,456		1,129,638
Outstanding warrants		17,721,088		17,768,314		17,819,616
Total		24,302,527		24,890,156		27,727,147

Amounts in the table above reflect the common stock equivalents of the noted instruments.

Segment and Geographic Information

Operating segments are defined as components of an enterprise (business activity from which it earns revenue and incurs expenses) for which discrete financial information is available and regularly reviewed by the chief operating decision maker in deciding how to allocate resources and in assessing performance. The Company’s chief operating decision maker (CODM) is its CEO. The Company views its operations and manages its business as a single operating and reporting segment. All assets of the Company were held in the United States as of December 31, 2017, 2016 and 2015.

Although all operations are based in the United States, the Company generated a portion of its revenue in prior years from customers outside of the United States. Information about the Company’s revenue from the different geographic regions for the years ended December 31, 2017, 2016 and 2015 is as follows (in thousands):

	For the Year Ended December 31,
	2017		2016		2015
United States	$	45	$	44	$	191
Europe		—		—		21
Other non-U.S.		—		—		24
Total	$	45	$	44	$	236

Recent Accounting Pronouncements

Application of New or Revised Accounting Standards – Not Yet Adopted

In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash. This guidance requires restricted cash and restricted cash equivalents to be included with the cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the consolidated statement of cash flows. ASU 2016-18 is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Early adoption is permitted, but the Company does not plan to adopt early. The evaluation of ASU 2016-18 has been completed and the adoption will not have a significant impact on the Company’s consolidated financial statements and disclosures.

In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Payments. This standard provides classification guidance for eight types of cash receipts and payments shown on the consolidated statement of cash flows, including proceeds from the settlement of insurance claims. ASU 2016-15 is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Early adoption is permitted, but the Company does not plan to adopt early. The evaluation of ASU 2016-15 has been completed and the adoption will not have a significant impact on the Company’s consolidated financial statements and disclosures.

In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. This new guidance is intended to present credit losses on available for sale debt securities as an allowance rather than as a write-down. ASU 2016-13 is effective for annual reporting periods, including interim periods within those annual periods, beginning after December 15, 2019, with early adoption permitted for those fiscal years beginning after December 15, 2018. Adoption of ASU 2016-13 is not expected to have a significant impact on the Company’s consolidated financial statements and disclosures.

In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842), which requires lessees to recognize assets and liabilities for operating leases with lease terms greater than twelve months in the balance sheet. The update also requires improved disclosures to help users of financial statements better understand the amount, timing and uncertainty of cash flows arising from leases. ASU 2016-02 is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, with early adoption permitted. The Company is currently evaluating the impact of the adoption of ASU 2016-02 on its financial statements and disclosures. The adoption is expected to result in a significant increase in the total assets and liabilities reported on the Company’s consolidated balance sheet.

In January 2016, the FASB issued ASU 2016-01, Financial Instruments – Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. The new standard principally affects accounting standards for equity investments, financial liabilities where the fair value option has been elected, and the presentation and disclosure requirements for financial instruments. Upon the effective date of the new standard, all equity investments in unconsolidated entities, other than those accounted for using the equity method of accounting, will generally, unless the investment does not have a readily determinable fair value, be measured at fair value through earnings. As a result of ASU 2016-01, effective January 1, 2018, the Company will account for its preferred stock investment in Viracta (investment) as an equity investment rather than cost method investment. Because the Company’s investment meets the practicability exception, the fair value will be estimated at its cost minus any impairment, plus or minus changes resulting from observable price changes. Additionally, changes in fair value will be recorded through other income (expense), net on the consolidated statements of operations. Other updates included in the new standard are not expected to have a significant impact on the Company’s consolidated financial statements and disclosures.

In May 2014, the FASB issued guidance codified in ASC Topic 606, ASU 2014-09, Revenue Recognition—Revenue from Contracts with Customers, which amends the guidance in former ASC Topic 605, Revenue Recognition, and was initially to be effective beginning January 1, 2017. On August 12, 2015, the FASB issued guidance which defers the effective date of ASC Topic 606 by one year to January 1, 2018 for public companies. This guidance requires that entities recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. ASU 2014-09 defines a five-step process to achieve this core principle and, in doing so, it is possible more judgment and estimates may be required within the revenue recognition process than are required under existing GAAP, including identifying performance obligations in a contract, estimating the amount of variable consideration to include in the transaction price and allocating the transaction price to each separate performance obligation. The new standard allows for two methods of adoption: (1) full retrospective adoption, meaning the standard is applied to all periods presented, or (2) modified retrospective adoption, meaning the cumulative effect of applying the new standard is recognized as an adjustment to the opening retained earnings balance.

The Company’s assessment of the new standard’s effect on its financial statements is complete based on review of the Company’s current contracts with customers. The Company currently believes that the timing of recognizing revenue for its license agreements with customers will not significantly change. The Company’s accounting for sales-based royalty payments from its licensing arrangements is not expected to change. However, the new standard no longer requires the transaction price to be fixed or determinable and certain variable consideration, such as event-based milestone payments, might be recognized prior to the occurrence or resolution of the contingent event (subject to a revenue reversal constraint). Given the current uncertainty surrounding these event-based milestone payments and minimal change to the Company’s accounting for existing sales-based royalty payments, the Company expects to record an immaterial adjustment to accumulated deficit upon adoption of the standard on January 1, 2018. The Company also expects to adopt the new standard using the modified retrospective approach.

The new standard requires disclosure of quantitative and qualitative information that enables users of financial statements to understand the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. The Company expects to expand its existing revenue disclosure upon adoption of the new standard to meet this requirement.

Financial Statement Details

12 Months Ended

Dec. 31, 2017

Financial Statement Details [Abstract]

Financial Statement Details

3. Financial Statement Details

Prepaid expenses and other current assets

As of December 31, 2017 and 2016, prepaid expenses and other current assets were made up of (in thousands):

	As of December 31,
	2017		2016
Interest receivable - marketable securities	$	764	$	1,484
Prepaid license fees		597		462
Prepaid insurance		572		531
Equipment deposits		482		482
Prepaid services		416		1,191
Prepaid rent		373		360
Insurance claim receivable		340		—
Prepaid supplies		210		—
Prepaid legal fees		—		350
Other		398		275
	$	4,152	$	5,135

Property, plant and equipment, net

As of December 31, 2017 and 2016, property, plant and equipment was made up of (in thousands):

	As of December 31,
	2017			2016
Construction in progress	$	42,281		$	6,939
Buildings		23,811			4,348
Equipment		9,625			5,458
Leasehold improvements		3,918			2,367
Software		1,092			769
Furniture & fixtures		302			203
		81,029			20,084
Accumulated depreciation		(4,303	)		(1,178	)
	$	76,726		$	18,906

Depreciation expense related to property, plant and equipment was $3.3 million, $1.0 million and $0.1 million for the years ended December 31, 2017, 2016 and 2015, respectively.

Buildings of $23.8 million are comprised of $19.5 million related to the purchased warehouse and distribution facility in El Segundo, California, originally accounted for as a capital lease (See Note 8 – Capital Lease) and $4.3 million under a financing lease representing the estimated fair market value of the building in Culver City, California, for which the Company is the “deemed owner” for accounting purposes only, and related non-normal tenant improvements. See Note 8 section Financing Lease Obligation.

Construction in progress as of December 31, 2017 includes the estimated fair value of $ 5.1 million for the Company’s build-to-suit lease related to its facility in El Segundo, California, for which the Company is the “deemed owner” for accounting purposes only. See Note 8 section Build-to-suit Lease.

Intangible assets, net

As of December 31, 2017 and 2016, intangible assets were made up of (in thousands):

	As of December 31,
	2017			2016
Technology license	$	9,042		$	9,042
Less accumulated amortization		(6,216	)		(3,956	)
	$	2,826		$	5,086

Amortization expense was $2.3 million, $2.6 million and $1.3 million for the years ended December 31, 2017, 2016 and 2015, respectively. Amortization for the Company’s technology license is included in research and development expense on the consolidated statement of operations.

Future estimated amortization expense related to the Company’s technology license for the next five years and thereafter is as follows (in thousands):

Years ending December 31:
2018		2,261
2019		565
2020		—
2021		—
2022		—
Thereafter		—
	$	2,826

The remaining amortization period for the technology license is 1.25 years.

Other assets

As of December 31, 2017 and 2016, other assets were made up of (in thousands):

	As of December 31,
	2017		2016
Restricted cash	$	179	$	179
Security deposit		127		137
Other		24		110
Equipment not placed in service		—		362
	$	330	$	788

Accrued expenses

As of December 31, 2017 and 2016, accrued expenses were made up of (in thousands):

	As of December 31,
	2017		2016
Accrued construction costs	$	6,212	$	1,243
Accrued bonus		1,930		1,732
Accrued professional and service fees		1,048		1,008
Accrued compensation		944		898
Accrued preclinical and clinical trial costs		521		662
Other		612		321
	$	11,267	$	5,864

Other current liabilities

As of December 31, 2017 and 2016, other current liabilities were made up of (in thousands):

	As of December 31,
	2017		2016
Deferred rent - current portion	$	520	$	197
Build-to-suit lease liability - current portion		334		281
Financing obligation - current portion		284		253
Other		235		160
	$	1,373	$	891

Investment income, net

Net investment income includes interest income from all bank accounts as well as marketable securities, dividend income, net realized gains or losses on sales of investments and the amortization of the premiums and discounts of the investments and is as follows for the years ended December 31, 2017, 2016 and 2015 (in thousands).

	For the Year Ended December 31,
	2017			2016			2015
Interest income	$	4,225		$	5,168		$	312
Investment amortization accretion expense, net		(1,597	)		(2,182	)		(38	)
Dividend income		—			—			213
Net realized gains on investments		37			111			2,501
	$	2,665		$	3,097		$	2,988

The interest income includes interest from the Company’s bank deposits. The Company did not recognize an impairment loss on any investments during the years ended December 31, 2017, 2016 and 2015.

Cost Method Investment	12 Months Ended
Cost Method Investment	Dec. 31, 2017
Investments All Other Investments [Abstract]
Cost Method Investment	4. Cost Method Investment In March 2017, the Company participated in a Series B convertible preferred stock financing and invested $8.5 million in Viracta Therapeutics, Inc. (Viracta), a clinical stage drug development company. The Company did not exercise the option to purchase up to an additional $8.5 million worth of shares of the Series B convertible preferred stock by September 30, 2017, the expiration date. In May 2017, the Company executed an exclusive worldwide license with Viracta to develop and commercialize Viracta’s proprietary histone deacetylase inhibitor drug candidate for use in combination with NK cell therapy and possibly additional therapies. See Note 7 for further information regarding the license. Based on the level of equity investment at risk, Viracta is not a VIE. The Company is not consolidating Viracta, but is accounting for this investment using the cost method because the preferred stock is not considered in-substance common stock and preferred stock does not have a readily determinable fair value. As of December 31, 2017, the Company did not estimate the fair value of this cost method investment as there were no events or changes in circumstances that may have had a significant adverse effect on the fair value of the investment. The $8.5 million cost of the investment is recorded in cost method investment in the consolidated balance sheet as of December 31, 2017.

Cash Equivalents and Marketable Securities

12 Months Ended

Dec. 31, 2017

Cash Equivalents And Marketable Securities [Abstract]

Cash Equivalents and Marketable Securities

5. Cash Equivalents and Marketable Securities

As of December 31, 2017, all of the Company’s marketable securities are classified as available-for-sale and are scheduled to mature within 3.7 years. At December 31, 2017 and 2016, the Company’s cash equivalents and marketable securities are detailed below (in thousands).

	December 31, 2017
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Current:
Government sponsored securities	$	19,261	$	—	$	(28	)	$	19,233
Corporate debt securities		82,188		5		(84	)		82,109
Foreign government bonds		6,441		—		(5	)		6,436
Subtotal current		107,890		5		(117	)		107,778
Noncurrent:
Government sponsored securities		2,760		—		(43	)		2,717
Corporate debt securities		27,109		—		(226	)		26,883
Subtotal noncurrent		29,869		—		(269	)		29,600
Total	$	137,759	$	5	$	(386	)	$	137,378

Included in foreign government bonds is $3.5 million of cash equivalents at December 31, 2017.

	December 31, 2016
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Current:
Commercial paper	$	22,252	$	21	$	(1	)	$	22,272
Corporate debt securities		165,605		40		(76	)		165,569
Foreign government bonds		5,004		—		(2	)		5,002
Subtotal current		192,861		61		(79	)		192,843
Noncurrent:
Government sponsored securities		17,018		2		(38	)		16,982
Corporate debt securities		69,414		71		(290	)		69,195
Foreign government bonds		1,405		—		(11	)		1,394
Subtotal noncurrent		87,837		73		(339	)		87,571
Total	$	280,698	$	134	$	(418	)	$	280,414

Included in corporate debt securities is $2.0 million of cash equivalents at December 31, 2016.

Available-for-sale investments that had been in an unrealized loss position for less than 12 months and for more than 12 months at December 31, 2017 and 2016 are as follows (in thousands):

	December 31, 2017
	Less than 12 months					More than 12 months
	Estimated Fair Value		Gross Unrealized Losses			Estimated Fair Value		Gross Unrealized Losses
Government sponsored securities	$	9,744	$	(20	)	$	12,205	$	(51	)
Corporate debt securities		67,522		(104	)		35,918		(206	)
Foreign government bonds		1,542		—			1,396		(5	)
Total	$	78,808	$	(124	)	$	49,519	$	(262	)

	December 31, 2016
	Less than 12 months					More than 12 months
	Estimated Fair Value		Gross Unrealized Losses			Estimated Fair Value		Gross Unrealized Losses
Government sponsored securities	$	17,204	$	(39	)	$	—	$	—
Corporate debt securities		150,320		(366	)		—		—
Foreign government bonds		6,396		(13	)		—		—
Total	$	173,920	$	(418	)	$	—	$	—

At December 31, 2017, 65 of the securities and bonds are in an unrealized loss position. The Company evaluated its securities for other-than-temporary impairment and concluded that the decline in value was primarily caused by current economic and market conditions. The Company does not intend to sell the investments and it is not more likely than not that the Company will be required to sell the investments before recovery of their amortized cost bases. Therefore, the Company did not recognize any other-than-temporary impairment loss during the years ended December 31, 2017, 2016 and 2015.

The Company recorded realized gains and losses on sales or maturities of available-for-sale securities as follows (in thousands):

	Gross Realized Gains		Gross Realized Losses			Net Realized Gains
2017	$	52	$	(15	)	$	37
2016		190		(79	)		111
2015		2,501		—			2,501

Fair Value Measurements

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Fair Value Measurements

6. Fair Value Measurements

Fair value is defined as an exit price that would be received from the sale of an asset or paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Authoritative guidance establishes a three-level hierarchy for disclosure that is based on the extent and level of judgment used to estimate the fair value of assets and liabilities.

Recurring Valuations

Financial assets and liabilities measured at fair value on a recurring basis are summarized below at December 31, 2017 and 2016 (in thousands):

	December 31, 2017
	Total		Level 1		Level 2		Level 3
Assets:
Current:
Cash and cash equivalents	$	23,872	$	20,374	$	3,498	$	—
Government sponsored securities		19,233		—		19,233		—
Corporate debt securities		82,109		—		82,109		—
Foreign government bonds		2,938		—		2,938		—
Noncurrent:
Government sponsored securities		2,717		—		2,717		—
Corporate debt securities		26,883		—		26,883		—
Total assets measured at fair value	$	157,752	$	20,374	$	137,378	$	—

	December 31, 2016
	Total		Level 1		Level 2		Level 3
Assets:
Current:
Cash and cash equivalents	$	8,083	$	6,078	$	2,005	$	—
Government sponsored securities		22,272		—		22,272		—
Corporate debt securities		163,564		—		163,564		—
Foreign government bonds		5,002		—		5,002		—
Noncurrent:
Government sponsored securities		16,982		—		16,982		—
Corporate debt securities		69,195		—		69,195		—
Foreign government bonds		1,394		—		1,394		—
Total assets measured at fair value	$	286,492	$	6,078	$	280,414	$	—

Non-recurring Valuation

Non-financial assets and liabilities are recognized at fair value subsequent to initial recognition when they are deemed to be other-than-temporarily impaired. There were no material non-financial assets and liabilities deemed to be other-than-temporarily impaired and measured at fair value on a non-recurring basis for the years ended December 31, 2017, 2016 and 2015.

Collaboration and License Agreements	12 Months Ended
Collaboration and License Agreements	Dec. 31, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Collaboration and License Agreements	7. Collaboration and License Agreements Collaborative Arrangements A collaborative arrangement is a contractual arrangement that involves a joint operating activity. These arrangements involve two or more parties who are (i) active participants in the activity, and (ii) exposed to significant risks and rewards dependent on the commercial success of the activity. Exclusive Co-Development Agreement In August 2016, the Company entered into an exclusive Co-Development Agreement (the Co-Development Agreement) with Altor BioScience Corporation (Altor), a related party (Note 9). Under the Co-Development Agreement, the Company and Altor agreed to exclusively collaborate on the development of therapeutic applications combining the Company’s proprietary natural killer cells with Altor's ALT-801 and/or ALT-803 products with respect to certain technologies and intellectual property rights as may be agreed between the parties for the purpose of jointly developing therapeutic applications of certain effector cell lines. The Company will be the lead developer for each product developed by the parties pursuant to the Co-Development Agreement unless otherwise agreed to under a given project plan. Under the terms of the Co-Development Agreement, both parties grant a co-exclusive, royalty free, fully paid-up, worldwide license, with the right to sublicense (only to a third-party contractor assisting with research and development activities under this Co-Development Agreement and subject to prior consent, not to be unreasonably withheld), under the intellectual property (IP), including the parties interest in the joint IP, solely to conduct any development activities agreed to by the steering committee as set forth in any development plan. Unless otherwise mutually agreed by the parties in the development plan for a project, the Company shall be responsible for all costs and expenses incurred by either party related to conducting clinical trials and other activities under each development program, including costs associated with patient enrollment, materials and supplies, third-party staffing and regulatory filings. Altor will supply free of charge sufficient amounts of Altor products for all pre-clinical requirements and all clinical requirements for up to 400 patients in phase I and/or phase II clinical trials, as required under the development plan for a project per the Co-Development agreement. Altor and the Company each will own an undivided interest in and to all rights, title and interest in and to the joint product rights. The Co-Development Agreement expires upon the fifth anniversary of the effective date. During the year ended December 31, 2017, the Company has dosed several patients with ALT-803 in its phase II Merkel cell carcinoma and our phase Ib/II pancreatic trials. No charges for supplies or milestones by Altor have been incurred in association with the above trial during the years ended December 31, 2017 and 2016. Joint Development and License Agreement In December 2014, the Company entered into a Joint Development and License Agreement with Sorrento Therapeutics, Inc. (Sorrento). The agreement expired in December 2017. Since no joint product candidates were identified during the exclusive term, Sorrento has no rights to use the Company’s NK cells or other technologies or intellectual property rights or to begin related research, development or commercialization activities and the Company is free to pursue, and is actively pursuing, research, development and commercialization activities with antibodies that may bind to various targets, including PDL1, CD19 and FLT3. Royalties and In-licensing Agreements Viracta License Agreement In May 2017, the Company entered into an agreement with Viracta to grant the Company exclusive world-wide rights to Viracta’s phase II drug candidate, VRx-3996, for use in combination with the Company’s platform of natural killer cell therapies. The Company’s Chairman and CEO is also the Vice Chairman of Viracta. In consideration for the license, the Company is obligated to pay to Viracta (i) mid-single digit percentage royalties of net sales of licensed products for therapeutic use; and (ii) milestone payments ranging from $10.0 million to $25.0 million for various regulatory approvals and cumulative net sales levels. The Company may terminate the agreement, in its sole discretion, in whole or on a product by product and/or country by country basis, at any time upon 90 days’ prior written notice. In addition, either party may terminate the agreement in the event of a material breach or for bankruptcy of the other party. Chemotherapeutisches Forschungsinstitut Georg-Speyer-Haus (GSH) and DRK-Blutspendedienst Baden-Wurttenberg-Hessen gGmbH (BSD) License Agreement In August 2015, the Company entered into a license agreement with GSH and BSD under which the Company was granted an exclusive license to certain GSH-BSD patents, materials and know-how that specifically targets ErbB2 expressing cancers. In addition, GSH granted the Company an exclusive license to certain GSH only technology and materials. In consideration for the licenses, the Company agreed to pay initial and annual licensing fees, regulatory and commercial milestones and low single-digit percentage royalties on net sales of licensed products. The royalty term shall continue in a particular country until the later of (i) the expiration of the valid patent claims in such country, or (ii) a specified period of time after the first commercial sale of licensed product in such country. The license agreement shall continue until no further payments are due at which time the licenses and rights will continue on a non-exclusive, royalty-free basis. The license agreement can be terminated earlier: (i) for material breach by either party after 60 days cure period, (ii) if the Company declares bankruptcy or insolvency, (iii) by the Company in its sole discretion upon 60 days prior written notice. The Company paid and expensed $1.1 million for the initial license fees in 2015 under the license, which was included in research and development expenses on the consolidated statements of operations for the year ended December 31, 2015. Annual license fees under the agreement begin in 2018. During the third quarter of 2017, GSH reached the first regulatory milestone of a receipt of the first Institutional Review Board (IRB) approval for the phase I glioblastoma study. The Company expensed $0.9 million for the first milestone payment under the agreement, which is included in research and development expenses on the consolidated statements of operations for the year ended December 31, 2017. No expense was recognized in 2016. Fox Chase Cancer Center License Agreement In 2004 and amended in 2008, the Company entered into an exclusive license agreement with Fox Chase Cancer Center (Fox Chase) for the exclusive, worldwide right to certain patents and know-how pertaining to CD16 receptors bearing NK-92 cell lines. In consideration for this exclusive license, the Company agreed to pay Fox Chase (i) low single-digit percentage royalties on net sales of licensed products for therapeutic and diagnostic use; and (ii) mid-twenties percentage royalties on any compensation the Company receives from sublicensees. The Fox Chase license was assigned to Brink Biologics as a part of the Spin-out (Note 10). As a result, the Company recorded no royalty expense for the years ended December 31, 2017 and 2016. The Company recorded royalty expense of $0.1 million for the year ended December 31, 2015 related to the Fox Chase Cancer Center License Agreement for the period of time before the Spin-out. Royalty expense is included in selling, general and administrative on the consolidated statements of operations. Rush University Medical Center License Agreement In 2004, the Company entered into a 12-year licensing agreement with Rush University Medical Center for the exclusive rights to license and grant sublicenses of certain intellectual property related to clinical use of NK-92. The Company is required to pay low to mid-single digit percentage royalties on net sales depending upon the various fields of studies and other factors. The Company is required to pay a minimum annual royalty of $25,000. The Rush University Medical Center License Agreement also provides for payments in the aggregate amount of $2.5 million upon the Company achieving various milestones, including upon (i) the completion of phase II clinical trial associated with the licensed intellectual property; (ii) the approval by the Food and Drug Administration (the FDA) of a new drug application for a licensed product; and (iii) the first year that sales of the licensed product equals or exceeds $0.3 million. The Rush University Medical Center License Agreement terminates on the 12th anniversary of the first payment of royalties, which occurred in 2006, at which point the license is deemed a perpetual, irrevocable, fully-paid royalty-free, exclusive license, and may be terminated earlier by either party for material breach. During the years ended December 31, 2017, 2016 and 2015, the Company recorded royalty expense of $25,000 each year, related to the Rush University Medical Center License Agreement. Royalty expense is included in selling, general and administrative on the consolidated statements of operations. No milestones were met during the years ended December 31, 2017, 2016 and 2015. Out-Licensing Agreement Intrexon License Agreement In February 2010, the Company entered into a 17-year license agreement with Intrexon Corporation (Intrexon) pursuant to which the Company granted to Intrexon a non-exclusive, worldwide, sublicensable license to research and sell products under certain patents relating to modified NK-92 cells that express Intrexon’s proprietary gene sequences for use as a therapeutic and prophylactic agent in humans in specified therapeutic areas. In consideration for the license agreement, Intrexon paid the Company a one-time fee of $0.4 million, which was recorded in deferred revenue and is amortized over the term of the license agreement. Intrexon will pay the following milestone payments: $0.1 million upon the first IND filing; $0.1 million upon the commencement of the first phase II clinical trial; $0.4 million upon the commencement of the first phase III clinical trial; and $0.5 million upon the first commercial sale relating to the licensed products. Intrexon is obligated to pay the Company a low single digit percentage royalty based on net sales of the licensed products by Intrexon and a mid-teen percentage royalty based on revenues received by Intrexon in connection with sublicenses of the licensed products. No milestone payments were due or received in the years ended December 31, 2017, 2016 and 2015, and, therefore, the Company recorded no milestone revenue for any of those years on the consolidated statements of operations.

Commitment and Contingencies

12 Months Ended

Dec. 31, 2017

Commitments And Contingencies Disclosure [Abstract]

Commitments and contingencies

8. Commitments and Contingencies

Contingencies

The Company records accruals for loss contingencies to the extent that the Company concludes it is probable that a liability has been incurred and the amount of the related loss can be reasonably estimated. The Company evaluates, on a quarterly basis, developments in legal proceedings and other matters that could cause a change in the potential amount of the liability recorded or of the range of potential losses disclosed. Additionally, the Company has reflected its right to insurance recoveries, limited to the extent of incurred or probable losses, as a receivable when such recoveries have been agreed to with its third-party insurers and receipt is deemed probable. This includes instances where the Company’s third-party insurers have agreed to reimburse certain legal defense costs incurred with the applicable law firms by the Company.

Securities Litigation

In March 2016, a putative securities class action complaint captioned Sudunagunta v. NantKwest, Inc., et al., No. 16-cv-01947 was filed in federal district court for the Central District of California related to the Company’s restatement of certain interim financial statements for the periods ended June 30, 2015 and September 30, 2015. A number of similar putative class actions were filed in federal and state court in California. The actions originally filed in state court were removed to federal court, and the various related actions have been consolidated. Plaintiffs assert causes of action for alleged violations of Sections 11 and 15 of the Securities Act of 1933 and Sections 10(b) and 20(a) of the Securities Exchange Act of 1934 and Rule 10b-5 promulgated thereunder. Plaintiffs seek unspecified damages, costs and attorneys’ fees, and equitable/injunctive or other relief on behalf of putative classes of persons who purchased or acquired the Company’s securities during various time periods from July 28, 2015 through March 11, 2016. In September 2017, the court denied defendants' motion to dismiss the third amended consolidated complaint. No trial date has been set. Management intends to vigorously defend these proceedings. At this time, the Company cannot predict how the Court will rule on the merits of the claims and/or the scope of the potential loss in the event of an adverse outcome. Therefore, based on the information available at present, the Company cannot reasonably estimate a range of loss for this action. Should the Company ultimately be found liable, the liability could have a material adverse effect on the Company’s results of operations for the period or periods in which it is incurred.

On September 6, 2016, a putative shareholder derivative complaint captioned Bushansky v. Soon-Shiong, et al., No. 37-2016-00030867-CU-SL-CTL was filed in California Superior Court, San Diego County also related to the Company’s restatement of certain interim financial statements. The complaint named as defendants the Company’s directors and outside auditor at the time of the IPO. The Company is named solely as a nominal defendant. The complaint alleges the directors breached their fiduciary duties to the Company and wasted corporate assets, and that the outside auditors committed malpractice. The complaint seeks, on behalf of the Company, unspecified damages, the return of directors’ salaries for unspecified periods, and injunctive relief. At this time, the Company cannot predict how the Court will rule on the merits of the claims and/or the scope of the potential loss in the event of an adverse outcome. In April 2017, the court entered a written order of dismissal after granting the Company’s motion to dismiss the California complaint based on a corporate charter provision specifying a Delaware forum. Plaintiffs have filed a notice of appeal. Should the Company ultimately be found liable, the liability could have a material adverse effect on the Company’s results of operations for the period or periods in which it is incurred.

In October 2017, the first of two putative stockholder derivative complaints was filed in the Delaware Court of Chancery. The Delaware actions have been consolidated as In re NantKwest, Inc. Derivative Litigation, Cons. C.A. No. 2017-0774- VCL. A consolidated complaint was filed asserting that various of the Company's current and former directors and officers breached their fiduciary duties to the Company based on factual allegations similar to those in the Sudunagunta and Bushansky actions. The complaint seeks damages and other relief on behalf of the Company, which is named solely as a nominal defendant. On February 5, 2018, the defendants filed a motion to dismiss the consolidated complaint. At this time, the Company cannot predict how the Court will rule on the merits of the claims and/or the scope of the potential loss in the event of an adverse outcome. Therefore, based on the information available at present, the Company cannot reasonably estimate a range of loss for this action. Should the Company ultimately be found liable, the liability could have a material adverse effect on the Company’s results of operations for the period or periods in which it is incurred.

The Company has reflected its right to insurance recoveries, limited to the extent of incurred or probable losses, as a receivable when such recoveries have been agreed to with its third-party insurers and receipt is deemed probable. This includes instances where the Company’s third-party insurers have agreed to reimburse certain legal defense costs incurred with applicable law firms by the Company. The amount of such receivable recorded at December 31, 2017 was $0.3 million included in prepaid expenses and current assets on the Company’s consolidated balance sheet.

Appeal of USPTO Decision

In March 2009, the Company received a final rejection in one of the Company’s original patent applications pertaining to certain limited methods of use claims for NK-92 from the U.S. Patent and Trademark Office (the USPTO), but the USPTO allowed claims on all of the other proposed claims, including other methods of use. The Company appealed this decision with the USPTO Board of Appeals and, in the fall of 2013, the Board of Appeals reversed the Examiner’s rejection of the claim to certain limited methods of use with NK-92, but affirmed the Examiner’s rejection of the remaining patent claims. In December 2013, the Company brought an action in the U.S. District Court for the Eastern District of Virginia to review the decision of the USPTO as the Company disagreed with the decision as to the certain limited non-allowed claims. On September 2, 2015, the U.S. District Court granted the USPTO’s motion for summary judgment. On September 24, 2015, the Company filed a notice of appeal to the United States Court of Appeals for the Federal Circuit. In September 2015, the USPTO filed a Motion for Expenses seeking $0.1 million for attorney’s fees and the USPTO’s expert witness fees. In February 2016, the U.S. District Court denied the USPTO’s Motion for Expenses for attorney’s fees and granted Director’s Motion for Expenses for the USPTO’s expert witness fees. The USPTO filed a notice of appeal on April 5, 2016. In May 2017, the Federal Circuit affirmed the U.S. District Court’s summary judgment ruling. The formal mandate was issued on June 26, 2017. In June 2017, the Federal Circuit reversed the U.S. District Court and remanded the case for the U.S. District Court to enter an award of $0.1 million in favor of the USPTO. On August 31, 2017, a majority of active Federal Circuit judges voted to vacate the June 2017 decision and hear the case en banc sua sponte. The USPTO filed its opening brief on November 15, 2017. The Company filed its opening brief on January 16, 2018. The USPTO filed its reply brief on January 31, 2018. Oral argument was heard on March 8, 2018. Based on the information available at present, the Company cannot reasonably estimate a range of loss for this action beyond the attorney and expert witness fees. Accordingly, the awarded fees have been accrued, but no liability associated with this action beyond the fees has been accrued. The Company is expensing legal costs associated with defending this litigation as the costs are incurred.

Contractual Obligations - Leases

The Company leases: (i) office space in Cardiff-by-the-Sea, California; (ii) a research and office facility in Woburn, Massachusetts; (iii) office space in Cary, North Carolina; (iv) a research and office facility in San Diego, California; (v) research and manufacturing space in Culver City, California from a related party (Note 9) and; (vi) a research and manufacturing facility in El Segundo, California, also from a related party (Note 9).

Capital Lease

In April 2017, the Company entered into an agreement to purchase a commercial building with approximately 36,434 square feet, located in El Segundo, California. The Company intends to use this facility as a warehouse and distribution facility as it is adjacent to the El Segundo, California, research and manufacturing facility. Upon the execution of the purchase agreement, the Company made a deposit of $5.0 million to the escrow holder and entered into a lease agreement related to this facility commencing on May 1, 2017. There was no monthly base rent under the lease. The escrow closed in September 2017 and the Company paid the remaining purchase price, including closing costs, of $15.3 million and terminated the lease agreement.

The Company had a bargain purchase option to purchase the building upon termination of the escrow period and, initially, accounted for the lease as a capital lease. Upon purchase of the building in September 2017, which resulted in the termination of the capital lease, the Company accounted for the transaction as a single transaction and the carrying amount of the asset was adjusted for any differences between the carrying amount of the lease obligation and the initial carrying amount of the asset.

Build-to-suit Lease

In September 2016, the Company entered into a lease agreement with 605 Doug St, LLC, a related party (Note 9), for approximately 24,250 square feet in El Segundo, California, which is to be converted to a research and development laboratory and a current Good Manufacturing Practices (cGMP) laboratory. The lease runs from July 2016 through July 2023. The Company has the option to extend the lease for an additional three year term through July 2026. The monthly rent is $0.1 million with annual increases of 3% beginning in July 2017. For the years ended December 31, 2017 and 2016, the Company recorded rent expense of $0.2 million and $0.1 million, respectively, which is reflected in research and development expense on the consolidated statement of operations.

The Company is responsible for costs to build out the laboratory and has incurred costs of approximately $30.0 million as of December 31, 2017, which is reflected in construction in progress as part of property, plant and equipment, net on the consolidated balance sheet. Additionally, in order for the facility to meet the Company's research and development and cGMP laboratory specifications, the Company is making certain structural changes to the facility as part of the conversion to laboratory space. As a result of these changes, the Company concluded that it is the “deemed owner” of the building (for accounting purposes only) during the construction period. Accordingly, the Company recorded a non-cash build-to-suit lease asset of $5.1 million, representing its estimate of the fair market value of the building, and a corresponding construction build-to-suit lease liability, recorded as a component of other current and non-current liabilities on the consolidated balance sheet as of December 31, 2017.

Upon completion of construction of this facility, the Company evaluates the de-recognition of the asset and liability under the provisions of ASC 840-40, Leases - Sale-Leaseback Transactions. However, if the Company does not comply with the provisions needed for sale-leaseback accounting, the lease will be accounted for as a financing obligation and lease payments will be attributed to (1) a reduction of the principal financing obligation; (2) imputed interest expense; and (3) land lease expense (which is considered an operating lease and a component of research and development expenses) representing an imputed cost to lease the underlying land of the facility. In addition, the underlying building asset will be depreciated over the building's estimated useful life, which is estimated at 39 years. At the conclusion of the lease term, the Company would de-recognize both the net book values of the asset and financing obligation.

Financing Lease Obligation

In November 2015, the Company entered into a facility license agreement with NantWorks (Note 9) for approximately 9,500 square feet of office space in Culver City, California, which has been converted to a research and development laboratory and a cGMP laboratory. The license was effective in May 2015 and extends through December 2020. The Company has the option to extend the license through December 2023. The monthly license fee is $47,000 with annual increases of 3% beginning in January 2017. The Company records the rent payments as (1) a reduction of the financing obligation; (2) imputed interest expense; and (3) rent expense on the imputed cost to lease the underlying land of the facility, which is considered an operating lease. For the years ended December 31, 2017, 2016 and 2015, the Company recorded rent expense of $0.2 million, $0.2 million and $0.2 million, respectively, which is reflected in research and development expense on the consolidated statement of operation.

Under the facility license agreement, the Company was responsible for costs to build out the laboratory and incurred costs of approximately $3.5 million. The Company concluded that it was the “deemed owner” of the building (for accounting purposes only) during the construction period. The Company recorded the build out costs as an asset with a corresponding build-to-suit liability, which was recorded as a component of other current and non-current liabilities on the consolidated balance sheet while the building was under construction.

Upon completion of construction of this building in August 2016, the Company evaluated the de-recognition of the asset and liability under the provisions of ASC 840-40, Leases – Sale-Leaseback Transactions. The Company determined that the lease does not meet the criteria for sale-leaseback accounting treatment, due to the continuing involvement in the project resulting from the significant collateral the Company provided to the landlord in the form of building improvements. As a result, the building is being accounted for as a financing obligation. The underlying assets of $4.3 million are depreciated over the building’s estimated useful life, which is 39 years. At the conclusion of the lease term, the Company will de-recognize both the net book values of the assets and financing obligation.

Operating Leases

In March 2016, the Company entered into a lease agreement for an approximately 7,893 square foot facility in Woburn, Massachusetts, for a research and development laboratory, related office and other related uses. The term of the lease is 48 months commencing on April 29, 2016. In June 2016, the lease was amended to add 260 square feet, for a total of 8,153 square feet. The base rent, including the amendment, is $19,000 per month with a $1 per square foot annual increase on each anniversary date.

In July 2015, the Company entered into an agreement for approximately 3,067 square feet of office space in Cary, North Carolina. The lease expired as of December 31, 2017, and the Company vacated the premises.

In June 2015, the Company entered into a lease agreement for an approximately 44,700 square foot facility in San Diego, California, for a research and development laboratory, related office and other related uses. The term of the lease extends for seven years commencing on August 1, 2016. The base rent is $0.2 million per month with 3% annual increases on each anniversary date. In July 2015, the Company entered into a sublease for the building with the then existing lessee for a term of one year commencing August 1, 2015. There was no fixed rent or operating expenses during the sublease term other than utilities. The Company is currently subleasing approximately 8,500 square feet of the premises to related parties (Note 9).

The Company leases a total of approximately 2,550 square feet of office space in Cardiff-by-the-Sea, California, for general office use, pursuant to an operating lease. The lease term was extended through August 31, 2018. Our total monthly lease payment is currently $13,200 per month. In August 2017, the Company subleased these premises for the remainder of the lease term for the same payment.

The Company recognizes rent expense under operating leases on a straight-line basis. Rent expense for the years ended December 31, 2017, 2016 and 2015 was $2.7 million, $2.7 million, $1.5 million, respectively.

The following table summarizes our future minimum lease payments at December 31, 2017 (in thousands). Common area maintenance costs and taxes are not included in these payments.

Years ending December 31:
2018	$	4,094
2019		4,108
2020		4,056
2021		3,435
2022		3,538
Thereafter		2,056
Total minimum lease payments	$	21,287

Related Party Agreements	12 Months Ended
Related Party Agreements	Dec. 31, 2017
Related Party Transactions [Abstract]
Related Party Agreements	9. Related Party Agreements The Company had related party agreements with Inex Bio, Inc. (Inex Bio) until the Company acquired a majority of Inex Bio shares. See Note 15 – Investment in Inex Bio, Inc. for further details. In June 2015, the Company spun out Brink Biologics, Inc. (Brink Biologics) and Coneksis, Inc. (Coneksis) (Note 10). The Company’s Chairman and CEO has a controlling interest in Brink Biologics and Coneksis. The Company’s Chairman and CEO founded and has a controlling interest in NantWorks, Inc. (NantWorks), which is a collection of multiple companies in the healthcare and technology space. The Company has entered into arrangements with NantWorks and certain affiliates of NantWorks, as described below, to facilitate the development of new genetically modified NK cells for the Company’s product pipeline. John Lee, M.D. and Leonard Sender, M.D., Inc., a professional medical corporation, dba Chan Soon-Shiong Institutes for Medicine (CSSIM) In 2017, the Company entered into multiple agreements with John Lee, M.D. and Leonard Sender, M.D., Inc., a professional medical corporation, dba Chan Soon-Shiong Institutes for Medicine (CSSIM), in El Segundo, California, to conduct various clinical trials. CSSIM is a related party as it is owned by two officers of the Company and NantWorks provides administrative services to CSSIM. One of the Company’s officers is the principal investigator for the trials on behalf of CSSIM. During the year ended December 31, 2017, $0.8 million has been recognized in research and development expense on the consolidated statement of operations. As of December 31, 2017, the Company owes CSSIM $0.8 million, which is included in due to related parties on the consolidated balance sheet. Tensorcom, Inc. In April 2017, the Company entered into a sublease agreement with Tensorcom, Inc. (Tensorcom) related to its San Diego, California, research and development laboratory and office space, with an initial lease from May 1, 2017 through April 30, 2018. The Company’s Chairman and CEO indirectly owns all of the outstanding equity of Tensorcom. The sublease agreement converts to a month-to-month lease after the initial lease term, not to exceed the expiration of the lease agreement between the Company and the third party landlord. After the initial term, the sublease agreement can be terminated by either party by providing a thirty day written notice. The sublease includes a portion of the premises consisting of approximately 6,557 rentable square feet of space. The monthly base rent is $25,000 per month, with an annual 3% increase. For the year ended December 31, 2017, the Company recognized $0.2 million in other income on the consolidated statement of operations under the sublease agreement. At December 31, 2017, there was no balance due between the parties. VivaBioCell S.p.A. In February 2017, the Company entered into a research grant agreement with VivaBioCell S.p.A. (VBC), an affiliated company of NantWorks, under which VBC will conduct research and development activities related to the Company’s NK cell lines using VBC’s proprietary technology. The Company paid $0.6 million to VBC, which is recorded in prepaid expenses and other current assets on the consolidated balance sheet, and expects to benefit from the research and development activities over a one year timeframe. For the year ended December 31, 2017, $0.6 million has been recognized in research and development expense on the consolidated statement of operations and prepaid expenses and other current assets on the consolidated balance sheet has been reduced by that amount. 605 Doug St. LLC In September 2016, the Company entered into a lease agreement with 605 Doug St, LLC, an entity owned by the Company’s Chairman and CEO, for approximately 24,250 square feet in El Segundo, California, which is to be converted to a research and development laboratory and a cGMP laboratory. The lease runs from July 2016 through July 2023. The Company has the option to extend the lease for an additional three year term through July 2026. The monthly rent is $0.1 million with annual increases of 3% beginning in July 2017. See Note 8 section Build-to-Suit Lease for further details on this lease. For the years ended December 31, 2017 and 2016, the Company recorded rent expense of $0.2 million and $0.1 million, respectively, which is reflected in research and development expense on the consolidated statement of operations. At December 31, 2017, no balance was due between the parties. Altor In August 2016, the Company entered into a Co-Development Agreement with Altor as described in Note 7. The Company’s Chairman and CEO is also the Chairman of Altor. Altor is a wholly owned subsidiary of NantCell Inc. (NantCell), and the Company’s Chairman and CEO is also the Chairman and CEO of NantCell and holds a greater than 20% ownership interest in Altor. No charges for supplies or milestones by Altor have been incurred in association with the above trial during the years ended December 31, 2017 and 2016. NantBio, Inc. In January 2018, the Company entered into a laboratory services agreement with NantBio, Inc. (NantBio) a NantWorks company. The agreement, effective December 1, 2017, includes a sublease of approximately 1,965 square feet of laboratory and office space at the Company’s San Diego, California, research facility. The term of the sublease is 24 months, but can be terminated by either party with 30 days prior written notice. The sublease agreement converts to a month-to-month lease after the initial term, not to exceed the expiration of the lease agreement between the Company and the landlord. The monthly sublease and service fee of $10,000 is subject to an annual 3% increase on the agreement anniversary date. The Company recognized $10,000 in other income on the consolidated statement of operations for the year ended December 31, 2017. At December 31, 2017, NantBio owes the Company $0.1 million. In March 2016, NantBio and the National Cancer Institute entered into a cooperative research and development agreement. The agreement covers NantBio and its affiliates, including the Company. Under the agreement, the parties are collaborating on the preclinical and clinical development of proprietary recombinant NK cells and monoclonal antibodies in monotherapy and in combination immunotherapies. The Company expects to benefit from the preclinical and clinical research conducted during the first and second year under this agreement and is providing the first and second year of funding under the five-year agreement. In April 2016 and April 2017, the Company paid $0.6 million to the National Cancer Institute as a prepayment for this first and second year of funding. The Company recognizes research and development expense ratably over a 12-month period and recorded $0.6 million and $0.5 million, respectively, of expense for the years ended December 31, 2017 and 2016. NantWorks Under the NantWorks shared services agreement executed in November 2015, but effective August 2015, NantWorks provides corporate, general and administrative, manufacturing strategy, research and development, regulatory and clinical trial strategy and other support services. The Company is charged for the services at cost plus reasonable allocations for indirect costs that relate to the employees providing the services. For the years ended December 31, 2017, 2016 and 2015, the Company recorded $3.6 million, $3.9 million and $1.8 million, respectively, to selling, general and administrative expense and $3.2 million, $2.1 million and $0.3 million, respectively, in research and development expense under this arrangement on the consolidated statement of operations. These amounts exclude certain general and administrative expenses provided by third party vendors directly for the Company’s benefit, which have been reimbursed to NantWorks based on those vendors’ invoiced amounts without markup by NantWorks. In June 2016, the Company amended the existing shared services agreement with NantWorks whereby the Company can provide support services to NantWorks and/or any of its affiliates. For the years ended December 31, 2017 and 2016, the Company recorded expense reimbursements of $0.4 million and $0.1 million, respectively, to selling, general and administrative expense and $1.0 million and $0.2 million, respectively, to research and development expense. The Company owed NantWorks a net amount of $1.5 million for all agreements between the two affiliates at December 31, 2017, which is included in due to related parties on the consolidated balance sheet. In November 2015, the Company entered into a facility license agreement with NantWorks, which became effective May 2015, for approximately 9,500 square feet in Culver City, California, which has been converted to a research and development laboratory and a cGMP laboratory. See Note 8 - Financing Lease Obligation for further details on this lease. The Company recorded rent expense of $0.2 million for each of the years ended December 31, 2017, 2016 and 2015, which is reflected in research and development expense on the consolidated statement of operations. NantOmics, LLC In June 2015, the Company entered into an agreement with NantOmics, LLC (NantOmics) to obtain genomic sequencing and proteomic analysis services, as well as related data management and bioinformatics services, exclusively from NantOmics. The Company will have rights to use the data and results generated from NantOmics’ services in connection with the performance of the particular oncology trial with respect to which the services were performed, but NantOmics will own the data and results, as well as any other intellectual property it creates in performing these services on the Company’s behalf. The Company is obligated to pay NantOmics a fixed, per sample fee, determined based on the type of services being provided. The agreement has an initial term of five years and renews automatically for successive one year periods, unless terminated earlier. For the years ended December 31, 2017, 2016 and 2015, the Company recorded operating expense of $0.1 million, $0.2 million and $0.1 million, respectively, to research and development under this arrangement on the consolidated statement of operations. The Company owed NantOmics $0.1 million at December 31, 2017. NanoCav LLC In June 2015, the Company entered into an agreement with NanoCav, LLC (NanoCav), a related party, pursuant to which the Company obtained access to NanoCav’s virus-free cell transfection technologies on a non-exclusive basis. Under the agreement, NanoCav will conduct certain, mutually-agreed feasibility studies, on a fee for service basis, to evaluate the use of its cell transfection technologies with the Company’s aNK platform products and non-proprietary NK cells. The agreement has an initial term of five years and renews automatically for successive one year periods, unless terminated earlier. In September 2015, the Company made a $45,000 feasibility study retainer payment as required by the agreement. For the years ended December 31, 2017, 2016 and 2015, the Company recorded operating expense of $0, $0.1 million and $0, respectively, to research and development under this arrangement on the consolidated statement of operations. At December 31, 2017, no balance was due to either party. NantCell Inc. In June 2015, the Company also entered into a supply agreement with NantCell pursuant to which the Company has the right to purchase NantCell’s proprietary bioreactors, made according to specifications mutually agreed to with NantCell. The Company also has the right to purchase reagents and consumables associated with such equipment from NantCell. When an upfront payment is made, it is included in prepaid expenses on the consolidated balance sheets until the product is received. The agreement has an initial term of five years and renews automatically for successive one year periods unless terminated earlier. During the year ended December 31, 2017, the Company purchased bioreactors resulting in $0.3 million in capitalized equipment on the consolidated balance sheet. Under the same agreement, the Company also has the right to purchase reagents and consumables associated with such equipment from NantCell. During the years ended December 31, 2017, 2016 and 2015, the Company recorded research and development expense of $0.3 million, $0.2 million and $0, respectively, on the consolidated statement of operations. At December 31, 2017, the Company owed NantCell $0 and has a prepaid balance of $0.2 million included in prepaid expenses and other current assets on the consolidated balance sheet.

Spin-out of Brink Biologics and Coneksis	12 Months Ended
Spin-out of Brink Biologics and Coneksis	Dec. 31, 2017
Spinout
Spin-out of Brink Biologics and Coneksis	10. Spin-out of Brink Biologics and Coneksis On June 9, 2015, the Company spun out its business related to testing and diagnostic products and services into the entity, Brink Biologics in exchange for all of the issued and outstanding shares of Brink Biologics, which were subsequently distributed by a dividend to our stockholders. Under the spin-out arrangement, the Company transferred to Brink Biologics all of the Company’s existing revenue-earning, non-exclusive license agreements that allow third parties to use the Company’s cell lines and intellectual property for non-clinical laboratory testing. In addition, the Company transferred or licensed to Brink Biologics the Company’s other assets associated with testing and diagnostics products and services. The Company granted to Brink Biologics worldwide, exclusive licenses to the use of certain cell lines limited to the field of in vitro and in vivo testing and diagnostic products and services, trademarks, intellectual property, and patents, including the Company’s rights under its license agreement with Fox Chase Cancer Center. As part of the agreement, the Company also has a non-exclusive license to any results and data arising from Brink Biologics’ use of the Company’s cell lines and intellectual property for the Company’s use for internal research purposes and outside of Brink Biologics’ field. In consideration for the license grants, Brink Biologics is obligated to pay the Company a low single-digit royalty on amounts received for the sale of licensed products and services, as well as a low single-digit percentage share of other revenue received by Brink Biologics from the grant of sublicenses under the Company’s rights. For the years ended December 31, 2017, 2016 and 2015, the Company recorded $25,000, $21,000 and $11,000, respectively, in revenue for royalties on the consolidated statement of operations. Brink Biologics and the Company have the right to terminate the license agreement under certain conditions. Also, as part of the spin-out arrangement, the Company has agreed to provide certain services to Brink Biologics for a transitional period on a fee-for-service basis. Invoices for services are to be issued monthly and payments are due 30 days from the date invoiced. In the years ended December 31, 2017, 2016 and 2015, the Company invoiced $0.1 million, $0.1 million and $22,000, respectively, for services to Brink Biologics, which are recorded in other income on the consolidated statement of operations. At December 31, 2017, Brink Biologics owes the Company $34,000 which is included in due from related parties on the consolidated balance sheet. On June 9, 2015, the Company spun out its business related to veterinary oncology into the entity, Coneksis in exchange for all of the issued and outstanding shares of Coneksis, which were subsequently distributed by a dividend to our stockholders. In connection with the spin-out arrangement, the Company granted to Coneksis worldwide, exclusive licenses for use of certain cell lines in the field of veterinary medical research and therapeutics, trademarks, intellectual property, and patents, including the Company’s rights under its license agreement with Fox Chase Cancer Center. As part of the agreement, the Company also has a non-exclusive license to any results and data arising from Coneksis’ use of the Company’s cell lines and intellectual property for the Company’s use for internal research purposes and outside of Coneksis’ field. In consideration for the license grants, Coneksis is obligated to pay the Company a single-digit royalty on amounts received for the sale of licensed products and services, as well as a single-digit percentage share of other revenue received by Coneksis from the grant of sublicenses under the Company’s rights. Coneksis and the Company have the right to terminate the license agreement under certain conditions. Also, as part of the spin-out arrangement, the Company agreed to provide certain services to Coneksis for a transitional period on a fee-for-service basis. Invoices for services are to be issued monthly and payments are due 30 days from the date invoiced. For the years ended December 31, 2017, 2016 and 2015, the Company invoiced Coneksis for service fees in the amount of $40,000, $19,000 and $6,000, which are recorded in other income on the consolidated statement of operations. At December 31, 2017, Coneksis owes the Company $0.1 million, which has been fully reserved. The Company determined it has a variable interest in both Brink Biologics and Coneksis through its royalty agreements. Based upon the level of equity investment at risk, Brink Biologics and Coneksis are considered VIEs. The Company considered whether it is the primary beneficiary of the Brink Biologics and Coneksis VIEs and required to consolidate the entities. As the Company does not control the research and development or the sales of the potential licensed or commercialized products, the Company does not direct the activities of Brink Biologics and Coneksis that most significantly impact their economic performance. Therefore, the Company determined that it is not the primary beneficiary of the entities and does not consolidate the Brink Biologics VIE and the Coneksis VIE. ASU No. 2014-08, Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity, amended the definition of a discontinued operation, and requires additional disclosures about discontinued operations, as well as disposal transactions that do not meet the discontinued operations criteria. Under the new guidance, only disposals of a component representing a strategic shift in operations, that has or will have a major impact on the Company’s operations or financial results, should be classified as discontinued operations. The spin-out of Banks Biologics and Coneksis did not have a major impact on the Company’s operations or financial results, and accordingly, are not being reported as discontinued operations.

Stockholders' Equity

12 Months Ended

Dec. 31, 2017

Equity [Abstract]

Stockholders' Equity

11. Stockholders’ Equity

Stock Repurchase—In November 2015, the board of directors approved a share repurchase program (the 2015 Share Repurchase Program) allowing the CEO or CFO, on behalf of the Company, to repurchase from time to time, in the open market or in privately negotiated transactions, up to $50.0 million of the Company’s outstanding shares of common stock, exclusive of any commissions, markups or expenses. The timing and amounts of any purchases will be based on market conditions and other factors, including price, regulatory requirements and other corporate considerations. The 2015 Share Repurchase Program does not require the purchase of any minimum number of shares and may be suspended, modified or discontinued at any time without prior notice. The Company expects to finance the purchases with existing cash balances. 2,157,944 shares were repurchased for a total of $15.8 million during the year ended December 31, 2016. No shares were repurchased under the program during the year ended December 31, 2015.

During the year ended December 31, 2017, the Company repurchased 3,633,610 shares of its common stock, at prices ranging between $3.10 per share and $5.00 per share for a total of $15.2 million, including $0.1 million of broker commissions on repurchases. The shares are formally retired through board approval upon repurchase. The Company accounted for the repurchases under the constructive retirement method and allocated the excess of the repurchase price over par value to accumulated deficit. At December 31, 2017, $19.1 million remained authorized for repurchase under the Company’s 2015 Share Repurchase Program.

A summary of common stock repurchases for the year ended December 31, 2017 is as follows:

	Total number of shares purchased		Average price paid per share		Total number of shares purchased as part of publicly announced plans or programs		Maximum approximate dollar value of shares that may yet be purchased under the plans or programs
March		300,000	$	3.50		300,000	$33.1 million
May		1,028,200	$	3.92		1,328,200	$29.1 million
June		1,744,009	$	4.18		3,072,209	$21.8 million
November		244,574	$	4.87		3,316,783	$20.6 million
December		316,827	$	4.94		3,633,610	$19.1 million
Total		3,633,610	$	4.16

Conversion—In June 2015, the board of directors and the requisite shareholders approved the conversion of Class A common stock to common stock. Each share of Class A common stock (the 2015 Conversion) converted into 1.00 share of common stock. Additionally, the number of authorized shares of common stock was increased from 80,000,000 to 100,000,000.

Forward Stock Split—On July 10, 2015, the Company amended its amended and restated certificate of incorporation effecting a 1.8515-for-1 forward stock split of its common stock. The forward stock split did not cause an adjustment to the par value or the authorized shares of the common stock or preferred stock. As a result of the forward stock split, the Company also adjusted the share and per-share amounts under its 2014 Equity Incentive Stock Plan and common stock warrant agreements with third parties. No fractional shares were issued in connection with the forward stock split. All disclosure of common shares and per common share data on the accompanying consolidated financial statements and related notes have been adjusted retroactively to reflect the forward stock split for all periods presented.

Amended and Restated Certificate of Incorporation—On July 31, 2015 the Company amended its Certificate of Incorporation to increase the number of authorized shares of common stock from 100,000,000 to 500,000,000.

Common Stock—In June 2015, the Company sold 3,698,695 shares of common stock in a private placement offering for net proceeds of $71.0 million after $28,000 of issuance costs. On July 8, 2015, the Company sold 364,638 shares of common stock in a private placement offering for gross proceeds of $7.0 million. On July 31, 2015, the Company closed its IPO and sold 9,531,200 shares of common stock for net proceeds of $221.5 million after underwriters’ discounts and commissions and offering expenses of $16.8 million. In addition, the Company completed a separate private placement concurrent with the completion of the IPO and sold 680,000 shares of common stock for proceeds of $17.0 million.

Class A Common Stock—On June 18, 2015, the Company repurchased 249,952 shares of Class A common stock from an employee at $19.20 per share for $4.8 million. This was not part of the November 2015 share repurchase program described above.

Common Stock Warrants—In March 2015, the board of directors approved the issuance of a stock option and a warrant to purchase Class A common stock to an officer of the Company (Note 12). In connection with its acquisition of Inex Bio in March 2015, the Company issued warrants to purchase 3,202,592 shares of Class A common stock with an exercise price of $2.00 per share (Note 15). In April 2015, the Company received $6.4 million for the full exercise of the warrants.

In April 2015, a warrant to purchase 114,822 shares of Class A common stock was exercised. The warrant, issued in 2010 in conjunction with a termination and release agreement, was initially exercisable at $2.44 per share, and was ultimately exercised at $1.76 per share. The warrant was exercisable through February 2020. The warrant included a provision that for a period through two years after a reverse merger, the exercise price of the warrant was protected against down-round financing unless 66.67% of shareholders consent to the new transaction. Pursuant to ASC Subtopic 815-15 and ASC Subtopic 815-40, the fair value of the warrant of $0.4 million was recorded as a derivative liability on the issuance date. The fair value of the warrant was estimated at the issuance date and was revalued at each reporting period and the exercise date using a Monte Carlo simulation. At April 30, 2015, the date of exercise, the Company recorded a derivative liability of approximately $1.5 million. The change in fair value of the derivative liability is included in other income (expense) on the consolidated statements of operations.

Common Stock Reserved for Future Issuance

The Company is authorized to issue up to a total of 500,000,000 shares of common stock, par value $0.0001 per share at December 31, 2017 and 2016. As of December 31, 2017 there were 79,021,878 shares of common stock issued and outstanding.

The following table summarizes the common shares reserved for issuance on exercise or vesting of various awards at December 31, 2017:

Issued and outstanding stock options			5,693,250
Issued and outstanding restricted stock units			888,189
Outstanding financing warrants			131,838
Outstanding officer warrants			17,589,250
Total shares reserved for future issuance			24,302,527

Stock-Based Compensation

12 Months Ended

Dec. 31, 2017

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

12. Stock-Based Compensation

2014 Equity Incentive Plan—In March 2014, the Company’s board of directors and stockholders approved the 2014 Equity Incentive Plan (2014 Plan) under which 11,109,000 shares of Class A common stock were reserved for the granting of ISOs, non-statutory stock options, stock appreciation rights, restricted stock awards, restricted stock units and performance awards to employees, directors and consultants. Recipients of stock awards are eligible to purchase shares of the Company’s common stock at an exercise price equal to no less than the estimated fair market value of such stock on the date of grant. The maximum term of awards granted under the 2014 Plan is ten years. Stock awards are generally not exercisable prior to the applicable vesting date, unless otherwise accelerated under the terms of the applicable stock plan agreement. Unvested shares of the Company’s common stock issued in connection with an early exercise allowed by the Company may be repurchased by the Company upon termination of the optionee’s service with the Company.

2015 Equity Incentive Plan—In July 2015, the Company’s board of directors adopted the 2015 Equity Incentive Plan (2015 Plan). The 2015 Plan permits the grant of incentive stock options, within the meaning of Section 422 of the Code, to the Company’s employees and for the grant of non-statutory stock options, restricted stock, restricted stock units, stock appreciation rights, performance units and performance shares to the Company’s employees, directors and consultants. A total of 2,659,117 shares are reserved for future grants pursuant to the 2015 Plan as of December 31, 2017. In addition, the shares reserved for future grants under the 2015 Plan will include shares subject to stock options or similar awards granted under the 2014 Plan that expire or terminate without having been exercised in full and shares issued pursuant to awards granted under the 2014 Plan that are forfeited to or repurchased by the Company (provided that the maximum number of shares that may be added to the 2015 Plan pursuant to this provision is 6,635,489 shares as of December 31, 2017).

Modification of Stock-based Awards to an Officer—On March 24, 2015, the Company granted a non-qualified stock option (the Option) and a warrant (the Warrant) to purchase 1,851,500 shares and 17,589,250 shares of the Company’s common stock, respectively, to an officer of the Company. The Option had an exercise price of $2.00 per share, a ten-year term and vests monthly over 40 months from the grant date. The Warrant had an exercise price of $2.00 per share, a three-year term and included performance-based vesting conditions.

Subsequent to the original grant date, the Company modified the terms and conditions of the Option and the Warrant, and on May 8, 2015, the Company and the officer reached a mutual agreement on the revised terms of the Option and the Warrant. By mutual agreement, the Company increased the exercise price of the Option from $2.00 per share to $2.20 per share and reduced the term of the Option from ten to four years. The Warrant’s vesting conditions changed from performance based to a combination of performance based for 10,183,250 shares, including modified performance milestones from the original grant, and service based for 7,406,000 shares. In addition, the Company revised the term of the Warrant from three to four years.

The Company treated these changes to the Option and the Warrant as modifications of the terms and conditions of an equity award. The change in the term and exercise price of the Option did not result in incremental stock compensation expense as the higher exercise price and shorter term reduced the overall value of the modified Option.

The change in the terms for the Warrant resulted in incremental compensation expense of $91.5 million, of which $53.0 million is recognized upon achievement of performance milestones and $38.5 million is recognized over the service period, since the fair value of the modified Warrant is higher than the original fair value. Incremental compensation expense of $12.0 million, $19.0 million and $53.8 million was recognized during the years ended December 31, 2017, 2016 and 2015, respectively, and the remaining $6.7 million is expected to be recognized over the remaining vesting period of 0.6 years.

Issuance of options and restricted stock units to Officers—In accordance with their employment agreements, the Company granted to its CEO and its President and Chief Administrative Officer upon the IPO a total of 1,455,450 options to purchase common stock with an exercise price of $25.00 per share and 970,300 restricted stock units representing the right to receive one share of the Company’s common stock for each restricted stock unit that becomes vested. The options and restricted stock units vested 50% at grant and the remaining 50% vested upon the first anniversary of the IPO.

Stock-Based Compensation

The following table presents all stock-based compensation as included on the Company’s consolidated statements of operations (in thousands):

	For the Year Ended December 31,
	2017		2016		2015
Stock-based compensation expense:
Warrants for common stock to an officer	$	31,584	$	50,502	$	141,901
Warrants for common stock to an officer and a former director related to Inex Bio, Inc. acquisition		—		—		22,747
Employee stock options		4,267		14,720		25,498
Non-employee stock options		—		—		3,300
Employee restricted stock units		894		8,166		17,505
Non-employee restricted stock units		252		464		270
	$	36,997	$	73,852	$	211,221
Stock-based compensation expense in operating expenses:
Research and development	$	102	$	852	$	1,221
Selling, general and administrative		36,895		73,000		210,000
	$	36,997	$	73,852	$	211,221

Stock Options

The following table summarizes stock option activity under all equity incentive plans for the years ended December 31, 2017, 2016 and 2015:

	Number of Shares			Weighted- Average Exercise Price		Aggregate Intrinsic Value (in 000)		Weighted- Average Remaining Contractual Life (in years)
Outstanding at December 31, 2014		5,138,410		$	0.85	$	5,298		9.7
Options granted		5,713,899		$	7.92
Options exercised		(1,127,105	)	$	0.86
Options forfeited/canceled		(947,311	)	$	1.87
Outstanding at December 31, 2015		8,777,893		$	5.36	$	116,273		7.2
Options exercised		(2,398,883	)	$	0.76
Options forfeited/canceled		(71,624	)	$	2.00
Outstanding at December 31, 2016		6,307,386		$	7.14	$	19,100		6.4
Options exercised		(614,136	)	$	1.88
Outstanding at December 31, 2017		5,693,250		$	7.71	$	11,920		5.3
Vested and Exercisable at December 31, 2017		5,114,656		$	8.33	$	10,073		5.7

The vested and exercisable shares at December 31, 2016 and 2015 were 5,210,756 and 4,844,857, respectively.

The following table provides a summary of options outstanding and vested as of December 31, 2017:

Exercise Prices	Number Outstanding		Weighted- Average Life (in years)		Number Exercisable		Weighted- Average Life (in years)
$0.22		134,800		6.2		134,800		6.2
$0.42		589,660		6.9		589,660		6.9
$1.76		699,060		7.0		699,060		7.0
$2.00		962,780		7.1		962,780		7.1
$2.20		1,851,500		1.2		1,272,906		1.2
$25.00		1,455,450		7.6		1,455,450		7.6
		5,693,250		5.3		5,114,656		5.7

The aggregate intrinsic value of stock options exercised during the years ended December 31, 2017, 2016 and 2015 was $1.7 million, $17.0 million and $2.4 million, respectively. The cash received from exercised options was $1.2 million, $1.4 million and $0.9 million, respectively, for the years ended December 31, 2017, 2016 and 2015.

The Company records equity instruments issued to non-employees as expense at the fair value over the related service period as determined in accordance with the authoritative guidance and periodically revalues the equity instruments as they vest. The Company granted to non-employees stock options for 231,437 shares during the year ended December 31, 2015. All non-employees with stock options terminated prior to December 31, 2015, so there has been no related expense since then. All vested options were exercised within 90 days of those terminations, in accordance with the Equity Incentive Plans. No options were granted to non-employees in 2016 or 2017.

The total unrecognized compensation cost related to non-vested stock options as of December 31, 2017 is $4.8 million, which is expected to be recognized over a weighted-average period of 1.2 years.

The Company uses a Black-Scholes option-pricing model to determine the fair value of stock-based compensation under ASC Topic 718, Stock Compensation. The assumptions used for employee and non-employee stock options are presented in the table below:

	For the Year Ended December 31,
	2015
	Employee Grants		Non-Employee Grants
Expected term (years)	4.0 - 5.5		8.4 - 9.9
Risk-free interest rate	1.5% - 1.8%		0% - 2.4%
Expected volatility		80%		80%
Dividend yield		0%		0%
Weighted-average measurement date fair value	$	12.08	$	15.25

The assumed dividend yield was based on the Company’s expectation of not paying dividends in the foreseeable future. The estimated volatility is based on a weighted-average calculation of a peer group of comparable companies whose share prices are publicly available. The risk-free interest rate assumption was based on the U.S. Treasury’s rates for U.S. Treasury zero-coupon bonds with maturities similar to those of the expected term of the award being valued. The weighted-average expected life of options was estimated using the average of the contractual term and the weighted-average vesting term of the options.

Restricted Stock Units

The following table summarizes the restricted stock units (RSUs) activity under the 2015 Plan:

	Number of Restricted Stock Units Outstanding			Weighted-Average Grant Date Fair Value
Unvested balance at December 31, 2014		—		$	—
Granted		1,614,788		$	21.86
Vested		(485,150	)	$	25.00
Unvested balance at December 31, 2015		1,129,638		$	20.51
Granted		407,800		$	7.76
Vested		(537,982	)	$	23.75
Forfeited/canceled		(185,000	)	$	11.75
Unvested balance at December 31, 2016		814,456		$	13.98
Granted		615,983		$	4.50
Vested		(244,209	)	$	15.82
Forfeited/canceled		(298,041	)	$	10.28
Unvested balance at December 31, 2017		888,189		$	8.14

During the years ended December 31, 2017, 2016 and 2015, the Company granted 77,250, 67,500 and 353,188 shares of RSUs, respectively, to non-employees. Of the 77,250 granted to non-employees, 27,250 shares were granted to employees of related companies under the Company’s shared services agreement with NantWorks (Note 9).

As of December 31, 2017, there was $4.1 million of unrecognized stock-based compensation expense related to RSUs that is expected to be recognized over a weighted-average period of 2.8 years. Of that amount, $3.1 million of unrecognized expense is related to employee grants with a weighted-average period of 2.9 years and $0.9 million expense is related to non-employee grants with a weighted-average period of 2.4 years that is impacted by periodic mark-to-market adjustments.

Warrants

The following table summarizes the Company’s warrant activity:

Outstanding at December 31, 2014	1,850,937
Warrants granted	20,791,842
Warrants exercised	(4,677,101	)
Warrants forfeited	(146,062	)
Outstanding at December 31, 2015	17,819,616
Warrants exercised	(51,302	)
Outstanding at December 31, 2016	17,768,314
Warrants exercised	(47,226	)
Outstanding at December 31, 2017	17,721,088
Vested and exercisable at December 31, 2017	16,425,038

The total unrecognized compensation cost related to non-vested warrants as of December 31, 2017 is $17.8 million, which is expected to be recognized over a weighted-average period of 0.6 years.

Common Stock Reserved for Future Grants under the 2015 Equity Incentive Plan

At December 31, 2017, the Company has reserved authorized shares of common stock for future grants of equity awards as follows:

Shares approved for 2015 Equity Incentive Plan	3,500,000
Shares remaining from 2014 Equity Incentive Plan	749,857
Total shares authorized under the 2015 Plan	4,249,857
Grants	(3,070,238	)
Forfeitures added back to available pool	947,063
Shares reserved for future grants as of December 31, 2015	2,126,682
Grants	(407,800	)
Add backs approved under the Plan:
Forfeitures added back to available pool	185,000
Net share settlement	225,754
Exercised option shares repurchased	615,392
Shares reserved for future grants as of December 31, 2016	2,745,028
Grants	(615,983	)
Add backs approved under the Plan:
Forfeitures added back to available pool	298,041
Net share settlement	232,031
Shares reserved for future grants as of December 31, 2017	2,659,117

Income Taxes

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Income Taxes

13. Income Taxes

The amount of loss before taxes is (in thousands):

	For the Year Ended December 31,
	2017			2016			2015
U.S. loss before taxes	$	(94,734	)	$	(118,743	)	$	(235,750	)
Foreign loss before taxes		(2,182	)		(2,638	)		(1,427	)
Loss before income taxes	$	(96,916	)	$	(121,381	)	$	(237,177	)

Income tax (benefit) expense for the years ended December 31, 2017, 2016 and 2015 consists of the following (in thousands):

	For the Year Ended December 31,
	2017			2016			2015
Current:
Federal	$	—		$	—		$	—
State		4			3			1
Foreign		—			—			—
Total Current		4			3			1
Deferred:
Federal		—			—			—
State		—			—			—
Foreign		(497	)		(575	)		(302	)
Total Deferred		(497	)		(575	)		(302	)
Income tax (benefit) expense	$	(493	)	$	(572	)	$	(301	)

The components that comprise the Company’s net deferred tax assets at December 31, 2017 and 2016 consist of the following (in thousands):

	As of December 31,
	2017			2016
Deferred tax assets:
Stock compensation	$	73,336		$	87,239
Net operating loss carryforwards		42,784			37,507
Leases and other accrued liabilities		1,868			2,096
Tax credits		845			—
Accrued compensation		682			808
Total deferred tax assets		119,515			127,650
Deferred tax liabilities:
Foreign intangibles		(499	)		(996	)
Depreciation and amortization		(494	)		(309	)
Total deferred tax liabilities		(993	)		(1,305	)
Net deferred tax assets		118,522			126,345
Valuation allowance		(119,020	)		(127,341	)
Net deferred tax liability	$	(498	)	$	(996	)

A reconciliation of the federal statutory income tax rate to the Company’s effective income tax rate is as follows:

	For the Year Ended December 31,
	2017				2016				2015
Tax computed at federal statutory rate		34.0		%		34.0		%		34.0		%
Section 382/383 NOL		—				8.6				(3.5	)
State income taxes, net of federal tax benefit		5.3				3.6				2.6
Tax rate adjustment		4.8				1.5				—
Tax Cuts and Jobs Act		(53.4	)			—				—
Research and development credits		0.6				1.3				0.1
Stock-based compensation		(0.3	)			(0.3	)			(0.4	)
Other		0.8				(0.5	)			(3.8	)
Valuation allowance		8.7				(47.7	)			(28.9	)
Effective income tax rate		0.5		%		0.5		%		0.1		%

On December 22, 2017, the President of the United States signed into law the Tax Cuts and Jobs Act (Act of 2017). The Act amends the Internal Revenue Code (IRC) to reduce tax rates and modify policies, credits, and deductions for individuals and businesses. For businesses, the Act of 2017 reduces the corporate tax rate from a maximum of 35% to a flat 21% rate. The rate reduction is effective on January 1, 2018. As a result of the rate reduction, the Company has reduced the deferred tax asset balance as of December 31, 2017 by $51.7 million. Due to the Company’s full valuation allowance position, the Company has also reduced the valuation allowance by the same amount. Due to uncertainties which currently exist in the interpretation of the provisions of the Act of 2017 regarding IRC Section 162(m), the Company has not completed its evaluation of the potential impacts of IRC Section 162(m) as amended by the Act of 2017 on its financial statements. Current provisional amounts are recorded in a manner consistent with interpreting the 2017 Act as not materially impacting the IRC 162(m) evaluation.

On December 22, 2017, Staff Accounting Bulletin No. 118 (SAB 118) was issued to address the application of U.S. GAAP when a registrant does not have the necessary information available, prepared, or analyzed (including computations) in reasonable detail to complete the accounting for certain income tax effects of the Act of 2017. In accordance with SAB 118, the Company has determined that there is no deferred tax benefit or expense with respect to the re-measurement of certain deferred tax assets and liabilities due to the full valuation allowance against net deferred tax assets. Additional analysis of the law and the impact to the Company will be performed and any impact will be recorded in the respective quarter in 2018.

Pursuant of IRC Sections 382 and 383, annual use of the Company's net operating loss and research and development credit carryforwards may be limited in the event a cumulative change in ownership of more than 50% occurs within a three-year period . The Company completed an IRC Section 382/383 analysis through 2017 regarding the limitation of net operating loss and research and development credit carryforwards. The Company has derecognized the deferred tax assets for net operating losses and federal and state research and development credits of $0.8 million from its deferred tax asset schedule as of December 31, 2017. The Company had previously derecognized $1.2 million deferred tax assets for net operating losses and federal and state research and development credits as of December 31, 2016. There is no impact to tax expense for the derecognition of the net operating losses and federal and state research and development credits due to the valuation allowance recorded against the deferred tax assets. Additionally, the Company has not recognized the deferred tax asset for research and development credits carryforwards as of December 31, 2017 because the Company is a part of a controlled group of affiliated companies with common ownership and cannot complete its calculation of the credit until the time that all members of the controlled group complete their analysis and calculation of qualified research expenditures. The Company does not expect that the unrecognized tax benefits will change within 12 months of this reporting date. Due to the existence of the valuation allowance, future changes in the Company's unrecognized tax benefits will not impact the Company's effective tax rate.

In assessing the realization of deferred tax assets, management considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. Management considers the scheduled reversal of deferred tax liabilities, projected future taxable income and tax planning strategies in making this assessment. Based on the level of historical operating results and the uncertainty of the economic conditions, the Company has recorded a full valuation allowance of $119.0 million at December 31, 2017. The change in the valuation allowance for the year end December 31, 2017 was a decrease of $8.3 million. The portion of the valuation allowance for deferred tax assets for which subsequently recognized tax benefits will be credited directly to contributed capital is $0.2 million.

The Company has not incurred any material interest or penalties as of the current reporting date with respect to income tax matters. The Company does not expect that there will be unrecognized tax benefits of a significant nature that will increase or decrease within 12 months of the reporting date. The Company is subject to U.S. federal income tax, as well as income tax in California and other states. The federal returns for tax years 2014 through 2017 remain open to examination; the California returns remain subject to examination for tax years 2013 through 2017. Carryforward attributes that were generated in years where the statute of limitations is closed may still be adjusted upon examination by the Internal Revenue Service or other respective tax authority. All other state jurisdictions remain open to examination.

At December 31, 2017, the Company has federal net operating losses (NOLs) of approximately $165.9 million, state NOLs of $136.2 million, and foreign NOLs of $0.2 million. The federal NOL carryforwards begin to expire in 2024, the state NOL carryforwards begin to expire in 2030 and the foreign NOL carryforwards begin to expire in 2022. At December 31, 2017, the Company also had federal research tax credit carryforwards of approximately $3.2 million and California research tax credits of $1.9 million. The federal research tax credit carryforwards begin to expire in 2034 and the state research tax credit carryforwards begin to expire in 2029.

The following table summarizes the changes to the amount of unrecognized tax benefits (in thousands):

Unrecognized tax benefits at December 31, 2015	$	1,203
Decrease for prior year tax positions		(1,203	)
Increase for prior year tax positions		2,578
Increase for current year tax positions		2,056
Unrecognized tax benefits at December 31, 2016		4,634
Decrease for prior year tax positions		(812	)
Increase for current year tax positions		2,755
Unrecognized tax benefits at December 31, 2017	$	6,577

Included in the balance of unrecognized tax benefits at December 31, 2017, is $6.0 million that, if recognized, would not impact the Company’s income tax benefit or effective tax rate as long as the deferred tax asset remains subject to a full valuation allowance. The Company does not expect any significant increases or decreases to our unrecognized tax benefits within the next 12 months.

Notes Payable	12 Months Ended
Notes Payable	Dec. 31, 2017
Debt Disclosure [Abstract]
Notes Payable	14. Notes Payable Settlement Agreement Note—In 2007, the Company entered into a settlement agreement with a former officer of the Company (the Settlement Agreement Note). The Settlement Agreement Note included a cash payment to the former officer of $0.3 million payable upon the Company’s receipt of any debt or equity financing. As part of the 2009 Convertible Notes financing, the Settlement Agreement Note was amended so that the Note will convert into Class A common stock at a conversion price of $2.44 per share on the second anniversary of Company being a publicly traded company. In March 2015, the Company entered into a Supplemental Agreement and General Release (the Supplemental Agreement) with the former officer related to the Settlement Agreement. As a result, (i) the Company agreed to pay $0.13 million in exchange for retiring the note and (ii) the former officer agreed to exercise a warrant from 2008 to purchase 32,675 shares of Class A common stock at an exercise price of $2.44 per share. The Settlement Agreement Note is no longer outstanding as of December 31, 2015 and the $0.13 million difference between the carrying value of the Settlement Agreement Note and the amount paid to retire the Settlement Agreement Note is reflected in other income on the consolidated statement of operations for the year ended December 31, 2015.

Investment In Inex Bio, Inc

12 Months Ended

Dec. 31, 2017

Schedule Of Investments [Abstract]

Investment in Inex Bio, Inc

15. Investment in Inex Bio, Inc.

In April 2012, the Company made a strategic decision to enter into a License Agreement with Inex Bio, Inc. (Inex Bio), a Republic of Korea corporation (the Inex License Agreement). Under the Inex License Agreement, the Company provided Inex Bio with an exclusive license to the Company’s technology to be used in products only in certain Asian countries. In exchange for the Inex License Agreement, the Company received a $0.3 million up-front license fee. In addition, the Company was eligible to receive milestone payments of up to $0.8 million based upon completion of clinical trials and a 5% royalty on net sales of applicable products using the aNK cells. No milestone payments were due or received for the years ended December 31, 2015, 2014 or 2013.

In May 2012, the Company acquired 57,000 shares of Inex Bio for $0.2 million, which represented 22.2% of the outstanding shares and 17.4% of the fully-diluted shares of Inex Bio. The Company accounted for its investment under the equity method. The Company reviewed its investment for impairment in accordance with ASC Topic 320, Investments—Debt and Equity Securities.

In February and March 2015, Inex Bio Holdings (Holdings), an entity owned fifty percent (50%) by Cambridge Equities, L.P., an entity in which Dr. Soon-Shiong, the Company’s CEO and one of the Company’s directors, is the sole member of its general partner, and fifty percent (50%) by Eragon Ventures, LLC, an entity of which Dr. Ji, one of our former directors, is managing member, acquired 220,000 shares or 67.3% of Inex Bio from third party owners for $1.1 million.

On March 30, 2015, the Company entered into a Stock Purchase Agreement with Holdings and the third party owners, pursuant to which the Company acquired all the remaining outstanding shares of Inex Bio not previously held by the Company.

The Company paid to the other owners of Inex Bio cash of $1.5 million and issued warrants to acquire 593,072 shares of the Company’s Class A common stock at an exercise price of $2.00 per share. The Company valued the warrants using the Black-Sholes option-pricing model with a stock price of $10.72 per share as of March 30, 2015, an expected term of 0.04 years, and a volatility of 80%. This resulted in a total fair value of the warrants of $5.2 million. In April 2015, the Company received $1.2 million for the full exercise of the warrants.

The Company recorded the transaction as an asset purchase because Inex Bio was a shell corporation without any employees or other significant assets and did not meet the definition of a business under ASC Topic 805, Business Combinations.

The purchase price paid to acquire Inex Bio from the other owners is as follows (in thousands):

Consideration	Total
Cash paid by Inex Bio Holdings, LLC	$	1,100
Cash paid by Company		1,482
Fair value of warrants		5,170
Aggregate purchase price	$	7,752

The following table summarizes the assets acquired and liabilities assumed (in thousands):

Cash	$	763
Intangible assets—reacquired rights of Company technology		8,636
Other assets		42
Investment in Inex Bio		(221	)
Deferred tax liability		(1,467	)
Accounts payable		(1	)
Total assets acquired and liabilities assumed	$	7,752

The license solely covers pending patent applications at this time. The Company will amortize the intangible assets related to the reacquired rights of the Company technology over 4 years, which represents the period until the next action date of the pending patent application in the territory of the license issued to Inex Bio.

The Company paid Holdings cash of $6.5 million and issued warrants to acquire 2,609,520 shares of the Company’s Class A common stock at an exercise price of $2.00 per share for its assistance in negotiating the acquisition of Inex Bio from the other owners. The Company valued the warrants using the Black-Sholes option-pricing model with a stock price of $10.72 per share as of March 30, 2015, an expected term of 0.04 years, and a volatility of 80%. This resulted in a fair value of total warrants of $22.7 million. In April 2015, the Company received $5.2 million for the full exercise of the warrants.

The following summarizes the net consideration paid to Holdings (in thousands):

Consideration	Total
Cash	$	6,518
Fair value of warrants		22,747
Less cash paid to acquire shares in Inex Bio		(1,100	)
Net consideration	$	28,165

The Company recorded compensation expense for the portion of the cash and warrants issued to Holdings that exceeded the fair value of the shares acquired consistent with ASC Topic 718. The Company recorded $22.7 million of stock-based compensation and $5.4 million of cash compensation to the Company’s CEO and the former director as a result of acquiring their interest in Inex Bio.

Summarized Quarterly Data (Unaudited)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Summarized Quarterly Data (Unaudited)

16. Summarized Quarterly Data (Unaudited)

The following financial information reflects all normal recurring adjustments that are, in the opinion of management, necessary for a fair statement of the results of the interim periods.

The table below presents unaudited quarterly data for fiscal 2017 and 2016 (in thousands, except for share and per share amounts):

	1st Quarter			2nd Quarter			3rd Quarter			4th Quarter
2017
Revenue	$	11		$	14		$	8		$	12
Operating expenses		25,475			23,834			24,450			25,406
Operating loss		(25,464	)		(23,820	)		(24,442	)		(25,394	)
Net loss		(24,515	)		(23,452	)		(23,969	)		(24,487	)
Net loss per share - basic and diluted	$	(0.30	)	$	(0.29	)	$	(0.30	)	$	(0.31	)
Shares used in calculating net loss per share - basic and diluted		82,138,438			81,440,816			79,440,591			79,358,861

	1st Quarter			2nd Quarter			3rd Quarter			4th Quarter
2016
Revenue	$	6		$	12		$	12		$	14
Operating expenses		31,622			34,977			32,787			25,157
Operating loss		(31,616	)		(34,965	)		(32,775	)		(25,143	)
Net loss		(30,677	)		(33,997	)		(31,897	)		(24,238	)
Net loss per share - basic and diluted	$	(0.38	)	$	(0.41	)	$	(0.39	)	$	(0.29	)
Shares used in calculating net loss per share - basic and diluted		81,574,709			81,959,248			82,154,219			82,235,571

Employee Benefits	12 Months Ended
Employee Benefits	Dec. 31, 2017
Compensation And Retirement Disclosure [Abstract]
Employee Benefits	17. Employee Benefits Defined Contribution Benefit Plan - In December 2015, the Company adopted a 401(k) retirement and savings plan (the 401(k) Plan) covering all employees. The 401(k) Plan allows employees to make pre- and post-tax contributions up to the maximum allowable amount set by the IRS. The Company, at its discretion, may make certain contributions to the 401(k) Plan. The Company made contributions of $0.4 million, $0.2 million and $4,000 during the years ended December 31, 2017, 2016 and 2015, respectively. Compensated Absences – Under the Company’s vacation policy, certain salaried employees are provided unlimited vacation leave. Therefore, the Company does not record an accrual for paid leave related to these employees since the Company is unable to reasonably estimate the compensated absences that these employees will take.

Subsequent Event	12 Months Ended
Subsequent Event	Dec. 31, 2017
Subsequent Events [Abstract]
Subsequent Event	18. Subsequent Event In January 2018, the Company executed two new agreements with CSSIM, a related party (Note 9), for clinical trials on a squamous cell carcinoma vaccine and a triple negative breast cancer vaccine. The two trials combined will cost up to $12.7 million, depending on the number of patients that will be enrolled.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Liquidity

As of December 31, 2017, the Company had an accumulated deficit of approximately $498.7 million. The Company also had negative cash flow from operations of approximately $48.8 million during the year ended December 31, 2017. The Company expects that it will likely need additional capital to further fund development of, and seek regulatory approvals for, its product candidates, and begin to commercialize any approved products.

The Company is currently focused primarily on the development of immunotherapeutic treatments for cancers and debilitating viral infections using targeted cancer killing cell lines, and believes such activities will result in the Company’s continued incurrence of significant research and development and other expenses related to those programs. If the clinical trials for any of the Company’s product candidates fail or produce unsuccessful results and those product candidates do not gain regulatory approval, or if any of the Company’s product candidates, if approved, fails to achieve market acceptance, the Company may never become profitable. Even if the Company achieves profitability in the future, it may not be able to sustain profitability in subsequent periods. The Company intends to cover its future operating expenses through cash and cash equivalents, marketable securities, and through a combination of equity offerings, debt financings, government or other third-party funding, marketing and distribution arrangements and other collaborations, strategic alliances and licensing arrangements. Additional financing may not be available to the Company when needed and, if available, financing may not be obtained on terms favorable to the Company or its stockholders.

While the Company expects its existing cash and cash equivalents and marketable securities will enable it to fund operations and capital expenditure requirements for the next twelve months, it may not have sufficient funds to reach commercialization. Failure to obtain adequate financing when needed may require the Company to delay, reduce, limit or terminate some or all of its development programs or future commercialization efforts or grant rights to develop and market product candidates that the Company might otherwise prefer to develop and market itself, which could adversely affect the Company’s ability to operate as a going concern. If the Company raises additional funds from the issuance of equity securities, substantial dilution to existing stockholders may result. If the Company raises additional funds by incurring debt financing, the terms of the debt may involve significant cash payment obligations, as well as covenants and specific financial ratios that may restrict the Company’s ability to operate its business.

Principles of Consolidation and Equity Investments

Use of Estimates

Risks and Uncertainties

Contingencies

Cash, Cash Equivalents and Marketable Securities

Property, Plant and Equipment

Buildings		39 years
Software		3 years
Laboratory equipment		5 years
Furniture & fixtures		5 years
IT equipment		3 years
Leasehold improvements		The lesser of the lease term or the life of the asset

Cost Method Investment

Intangible Assets

Patents

The Company expenses patent costs, including related legal costs, as incurred and records such costs within general and administrative expenses on the consolidated statements of operations.

Impairments

Fair Value of Financial Instruments

The three tiers are defined as follows:

•

Level 3— Valuations based on inputs that are unobservable and significant to the overall fair value measurement.

The Company utilizes a third-party pricing service to assist in obtaining fair value pricing for investments. Inputs are documented in accordance with the fair value disclosure hierarchy.

Preclinical and Clinical Trial Accruals

Transactions with Related Parties

Lease Obligations

Income Taxes

Stock Repurchases

Revenue Recognition and Deferred Revenue

The Company records any amounts received prior to satisfying the revenue recognition criteria as deferred revenue on the accompanying consolidated balance sheets.

Research and Development Costs

Stock-Based Compensation

Litigation Costs

We expense legal fees as they are incurred.

Comprehensive Loss

Basic and Diluted Net Loss Per Share of Common Stock

Basic and Diluted Net Loss per Share of Common Stock

	As of December 31,
	2017		2016		2015
Outstanding options		5,693,250		6,307,386		8,777,893
Outstanding restricted stock units		888,189		814,456		1,129,638
Outstanding warrants		17,721,088		17,768,314		17,819,616
Total		24,302,527		24,890,156		27,727,147

Amounts in the table above reflect the common stock equivalents of the noted instruments.

Segment and Geographic Information

	For the Year Ended December 31,
	2017		2016		2015
United States	$	45	$	44	$	191
Europe		—		—		21
Other non-U.S.		—		—		24
Total	$	45	$	44	$	236

Recent Accounting Pronouncements

Application of New or Revised Accounting Standards – Not Yet Adopted

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Schedule of Estimated Useful Lives of Property, Plant and Equipment

Depreciation of property, plant and equipment is calculated using the straight-line method over the estimated useful lives of the assets, as follows:

Buildings		39 years
Software		3 years
Laboratory equipment		5 years
Furniture & fixtures		5 years
IT equipment		3 years
Leasehold improvements		The lesser of the lease term or the life of the asset

Securities Excluded from the Computation of Potentially Dilutive Securities

The following table details those securities that have been excluded from the computation of potentially dilutive securities:

	As of December 31,
	2017		2016		2015
Outstanding options		5,693,250		6,307,386		8,777,893
Outstanding restricted stock units		888,189		814,456		1,129,638
Outstanding warrants		17,721,088		17,768,314		17,819,616
Total		24,302,527		24,890,156		27,727,147

Amounts in the table above reflect the common stock equivalents of the noted instruments.

Schedule of Revenue from Different Geographic Regions

Information about the Company’s revenue from the different geographic regions for the years ended December 31, 2017, 2016 and 2015 is as follows (in thousands):

	For the Year Ended December 31,
	2017		2016		2015
United States	$	45	$	44	$	191
Europe		—		—		21
Other non-U.S.		—		—		24
Total	$	45	$	44	$	236

Financial Statement Details (Tables)

12 Months Ended

Dec. 31, 2017

Financial Statement Details [Abstract]

Prepaid Expenses and Other Current Assets

As of December 31, 2017 and 2016, prepaid expenses and other current assets were made up of (in thousands):

	As of December 31,
	2017		2016
Interest receivable - marketable securities	$	764	$	1,484
Prepaid license fees		597		462
Prepaid insurance		572		531
Equipment deposits		482		482
Prepaid services		416		1,191
Prepaid rent		373		360
Insurance claim receivable		340		—
Prepaid supplies		210		—
Prepaid legal fees		—		350
Other		398		275
	$	4,152	$	5,135

Property, Plant and Equipment, Net

As of December 31, 2017 and 2016, property, plant and equipment was made up of (in thousands):

	As of December 31,
	2017			2016
Construction in progress	$	42,281		$	6,939
Buildings		23,811			4,348
Equipment		9,625			5,458
Leasehold improvements		3,918			2,367
Software		1,092			769
Furniture & fixtures		302			203
		81,029			20,084
Accumulated depreciation		(4,303	)		(1,178	)
	$	76,726		$	18,906

Intangible Assets, Net

As of December 31, 2017 and 2016, intangible assets were made up of (in thousands):

	As of December 31,
	2017			2016
Technology license	$	9,042		$	9,042
Less accumulated amortization		(6,216	)		(3,956	)
	$	2,826		$	5,086

Future Estimated Amortization Expense

Future estimated amortization expense related to the Company’s technology license for the next five years and thereafter is as follows (in thousands):

Years ending December 31:
2018		2,261
2019		565
2020		—
2021		—
2022		—
Thereafter		—
	$	2,826

Other Assets

As of December 31, 2017 and 2016, other assets were made up of (in thousands):

	As of December 31,
	2017		2016
Restricted cash	$	179	$	179
Security deposit		127		137
Other		24		110
Equipment not placed in service		—		362
	$	330	$	788

Accrued Expenses

As of December 31, 2017 and 2016, accrued expenses were made up of (in thousands):

	As of December 31,
	2017		2016
Accrued construction costs	$	6,212	$	1,243
Accrued bonus		1,930		1,732
Accrued professional and service fees		1,048		1,008
Accrued compensation		944		898
Accrued preclinical and clinical trial costs		521		662
Other		612		321
	$	11,267	$	5,864

Other Current Liabilities

As of December 31, 2017 and 2016, other current liabilities were made up of (in thousands):

	As of December 31,
	2017		2016
Deferred rent - current portion	$	520	$	197
Build-to-suit lease liability - current portion		334		281
Financing obligation - current portion		284		253
Other		235		160
	$	1,373	$	891

Investment Income, Net

	For the Year Ended December 31,
	2017			2016			2015
Interest income	$	4,225		$	5,168		$	312
Investment amortization accretion expense, net		(1,597	)		(2,182	)		(38	)
Dividend income		—			—			213
Net realized gains on investments		37			111			2,501
	$	2,665		$	3,097		$	2,988

Cash Equivalents and Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2017

Cash Equivalents And Marketable Securities [Abstract]

Schedule of Cash Equivalents and Marketable Securities Available-for-Sale

	December 31, 2017
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Current:
Government sponsored securities	$	19,261	$	—	$	(28	)	$	19,233
Corporate debt securities		82,188		5		(84	)		82,109
Foreign government bonds		6,441		—		(5	)		6,436
Subtotal current		107,890		5		(117	)		107,778
Noncurrent:
Government sponsored securities		2,760		—		(43	)		2,717
Corporate debt securities		27,109		—		(226	)		26,883
Subtotal noncurrent		29,869		—		(269	)		29,600
Total	$	137,759	$	5	$	(386	)	$	137,378

	December 31, 2016
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Current:
Commercial paper	$	22,252	$	21	$	(1	)	$	22,272
Corporate debt securities		165,605		40		(76	)		165,569
Foreign government bonds		5,004		—		(2	)		5,002
Subtotal current		192,861		61		(79	)		192,843
Noncurrent:
Government sponsored securities		17,018		2		(38	)		16,982
Corporate debt securities		69,414		71		(290	)		69,195
Foreign government bonds		1,405		—		(11	)		1,394
Subtotal noncurrent		87,837		73		(339	)		87,571
Total	$	280,698	$	134	$	(418	)	$	280,414

Available-for-Sale Investments in Unrealized Loss Position

Available-for-sale investments that had been in an unrealized loss position for less than 12 months and for more than 12 months at December 31, 2017 and 2016 are as follows (in thousands):

	December 31, 2017
	Less than 12 months					More than 12 months
	Estimated Fair Value		Gross Unrealized Losses			Estimated Fair Value		Gross Unrealized Losses
Government sponsored securities	$	9,744	$	(20	)	$	12,205	$	(51	)
Corporate debt securities		67,522		(104	)		35,918		(206	)
Foreign government bonds		1,542		—			1,396		(5	)
Total	$	78,808	$	(124	)	$	49,519	$	(262	)

	December 31, 2016
	Less than 12 months					More than 12 months
	Estimated Fair Value		Gross Unrealized Losses			Estimated Fair Value		Gross Unrealized Losses
Government sponsored securities	$	17,204	$	(39	)	$	—	$	—
Corporate debt securities		150,320		(366	)		—		—
Foreign government bonds		6,396		(13	)		—		—
Total	$	173,920	$	(418	)	$	—	$	—

Schedule of Realized Gains and Losses on Sales or Maturities of Available-for-Sale Securities

The Company recorded realized gains and losses on sales or maturities of available-for-sale securities as follows (in thousands):

	Gross Realized Gains		Gross Realized Losses			Net Realized Gains
2017	$	52	$	(15	)	$	37
2016		190		(79	)		111
2015		2,501		—			2,501

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Summary of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis

Financial assets and liabilities measured at fair value on a recurring basis are summarized below at December 31, 2017 and 2016 (in thousands):

	December 31, 2017
	Total		Level 1		Level 2		Level 3
Assets:
Current:
Cash and cash equivalents	$	23,872	$	20,374	$	3,498	$	—
Government sponsored securities		19,233		—		19,233		—
Corporate debt securities		82,109		—		82,109		—
Foreign government bonds		2,938		—		2,938		—
Noncurrent:
Government sponsored securities		2,717		—		2,717		—
Corporate debt securities		26,883		—		26,883		—
Total assets measured at fair value	$	157,752	$	20,374	$	137,378	$	—

	December 31, 2016
	Total		Level 1		Level 2		Level 3
Assets:
Current:
Cash and cash equivalents	$	8,083	$	6,078	$	2,005	$	—
Government sponsored securities		22,272		—		22,272		—
Corporate debt securities		163,564		—		163,564		—
Foreign government bonds		5,002		—		5,002		—
Noncurrent:
Government sponsored securities		16,982		—		16,982		—
Corporate debt securities		69,195		—		69,195		—
Foreign government bonds		1,394		—		1,394		—
Total assets measured at fair value	$	286,492	$	6,078	$	280,414	$	—

Commitment and Contingencies (Tables)

12 Months Ended

Dec. 31, 2017

Commitments And Contingencies Disclosure [Abstract]

Summary of Future Minimum Lease Payments

The following table summarizes our future minimum lease payments at December 31, 2017 (in thousands). Common area maintenance costs and taxes are not included in these payments.

Years ending December 31:
2018	$	4,094
2019		4,108
2020		4,056
2021		3,435
2022		3,538
Thereafter		2,056
Total minimum lease payments	$	21,287

Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2017

Equity [Abstract]

Summary of Common Stock Repurchases

A summary of common stock repurchases for the year ended December 31, 2017 is as follows:

	Total number of shares purchased		Average price paid per share		Total number of shares purchased as part of publicly announced plans or programs		Maximum approximate dollar value of shares that may yet be purchased under the plans or programs
March		300,000	$	3.50		300,000	$33.1 million
May		1,028,200	$	3.92		1,328,200	$29.1 million
June		1,744,009	$	4.18		3,072,209	$21.8 million
November		244,574	$	4.87		3,316,783	$20.6 million
December		316,827	$	4.94		3,633,610	$19.1 million
Total		3,633,610	$	4.16

Summary Of Common Stock Reserved For Issuance

The following table summarizes the common shares reserved for issuance on exercise or vesting of various awards at December 31, 2017:

Issued and outstanding stock options			5,693,250
Issued and outstanding restricted stock units			888,189
Outstanding financing warrants			131,838
Outstanding officer warrants			17,589,250
Total shares reserved for future issuance			24,302,527

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2017

Stock Based Compensation Expenses Included on Operations Statement

The following table presents all stock-based compensation as included on the Company’s consolidated statements of operations (in thousands):

	For the Year Ended December 31,
	2017		2016		2015
Stock-based compensation expense:
Warrants for common stock to an officer	$	31,584	$	50,502	$	141,901
Warrants for common stock to an officer and a former director related to Inex Bio, Inc. acquisition		—		—		22,747
Employee stock options		4,267		14,720		25,498
Non-employee stock options		—		—		3,300
Employee restricted stock units		894		8,166		17,505
Non-employee restricted stock units		252		464		270
	$	36,997	$	73,852	$	211,221
Stock-based compensation expense in operating expenses:
Research and development	$	102	$	852	$	1,221
Selling, general and administrative		36,895		73,000		210,000
	$	36,997	$	73,852	$	211,221

Summarizes Stock Option Activity Under Equity Intensive Plan

The following table summarizes stock option activity under all equity incentive plans for the years ended December 31, 2017, 2016 and 2015:

	Number of Shares			Weighted- Average Exercise Price		Aggregate Intrinsic Value (in 000)		Weighted- Average Remaining Contractual Life (in years)
Outstanding at December 31, 2014		5,138,410		$	0.85	$	5,298		9.7
Options granted		5,713,899		$	7.92
Options exercised		(1,127,105	)	$	0.86
Options forfeited/canceled		(947,311	)	$	1.87
Outstanding at December 31, 2015		8,777,893		$	5.36	$	116,273		7.2
Options exercised		(2,398,883	)	$	0.76
Options forfeited/canceled		(71,624	)	$	2.00
Outstanding at December 31, 2016		6,307,386		$	7.14	$	19,100		6.4
Options exercised		(614,136	)	$	1.88
Outstanding at December 31, 2017		5,693,250		$	7.71	$	11,920		5.3
Vested and Exercisable at December 31, 2017		5,114,656		$	8.33	$	10,073		5.7

Summary of Options Outstanding and Vested

The following table provides a summary of options outstanding and vested as of December 31, 2017:

Exercise Prices	Number Outstanding		Weighted- Average Life (in years)		Number Exercisable		Weighted- Average Life (in years)
$0.22		134,800		6.2		134,800		6.2
$0.42		589,660		6.9		589,660		6.9
$1.76		699,060		7.0		699,060		7.0
$2.00		962,780		7.1		962,780		7.1
$2.20		1,851,500		1.2		1,272,906		1.2
$25.00		1,455,450		7.6		1,455,450		7.6
		5,693,250		5.3		5,114,656		5.7

Weighted Average of Fair Value of Options Under Black-Scholes Option-Pricing Model

	For the Year Ended December 31,
	2015
	Employee Grants		Non-Employee Grants
Expected term (years)	4.0 - 5.5		8.4 - 9.9
Risk-free interest rate	1.5% - 1.8%		0% - 2.4%
Expected volatility		80%		80%
Dividend yield		0%		0%
Weighted-average measurement date fair value	$	12.08	$	15.25

Restricted Stock Units (RSUs) Activity

The following table summarizes the restricted stock units (RSUs) activity under the 2015 Plan:

	Number of Restricted Stock Units Outstanding			Weighted-Average Grant Date Fair Value
Unvested balance at December 31, 2014		—		$	—
Granted		1,614,788		$	21.86
Vested		(485,150	)	$	25.00
Unvested balance at December 31, 2015		1,129,638		$	20.51
Granted		407,800		$	7.76
Vested		(537,982	)	$	23.75
Forfeited/canceled		(185,000	)	$	11.75
Unvested balance at December 31, 2016		814,456		$	13.98
Granted		615,983		$	4.50
Vested		(244,209	)	$	15.82
Forfeited/canceled		(298,041	)	$	10.28
Unvested balance at December 31, 2017		888,189		$	8.14

Summary of Warrant Activity

The following table summarizes the Company’s warrant activity:

Outstanding at December 31, 2014	1,850,937
Warrants granted	20,791,842
Warrants exercised	(4,677,101	)
Warrants forfeited	(146,062	)
Outstanding at December 31, 2015	17,819,616
Warrants exercised	(51,302	)
Outstanding at December 31, 2016	17,768,314
Warrants exercised	(47,226	)
Outstanding at December 31, 2017	17,721,088
Vested and exercisable at December 31, 2017	16,425,038

2015 Equity Incentive Plan

Reserved Authorized Shares Of Common Stock For Future Grants Of Equity Awards

At December 31, 2017, the Company has reserved authorized shares of common stock for future grants of equity awards as follows:

Shares approved for 2015 Equity Incentive Plan	3,500,000
Shares remaining from 2014 Equity Incentive Plan	749,857
Total shares authorized under the 2015 Plan	4,249,857
Grants	(3,070,238	)
Forfeitures added back to available pool	947,063
Shares reserved for future grants as of December 31, 2015	2,126,682
Grants	(407,800	)
Add backs approved under the Plan:
Forfeitures added back to available pool	185,000
Net share settlement	225,754
Exercised option shares repurchased	615,392
Shares reserved for future grants as of December 31, 2016	2,745,028
Grants	(615,983	)
Add backs approved under the Plan:
Forfeitures added back to available pool	298,041
Net share settlement	232,031
Shares reserved for future grants as of December 31, 2017	2,659,117

- Definition

Tabular disclosure of warrants or rights issued. Warrants and rights outstanding are derivative securities that give the holder the right to purchase securities (usually equity) from the issuer at a specific price within a certain time frame. Warrants are often included in a new debt issue to entice investors by a higher return potential. The main difference between warrants and call options is that warrants are issued and guaranteed by the company, whereas options are exchange instruments and are not issued by the company. Also, the lifetime of a warrant is often measured in years, while the lifetime of a typical option is measured in months. Disclose the title of issue of securities called for by warrants and rights outstanding, the aggregate amount of securities called for by warrants and rights outstanding, the date from which the warrants or rights are exercisable, and the price at which the warrant or right is exercisable.

+ References + Details

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Summary of Loss Before Taxes

The amount of loss before taxes is (in thousands):

	For the Year Ended December 31,
	2017			2016			2015
U.S. loss before taxes	$	(94,734	)	$	(118,743	)	$	(235,750	)
Foreign loss before taxes		(2,182	)		(2,638	)		(1,427	)
Loss before income taxes	$	(96,916	)	$	(121,381	)	$	(237,177	)

Summary of Income Tax (Benefit) Expense

Income tax (benefit) expense for the years ended December 31, 2017, 2016 and 2015 consists of the following (in thousands):

	For the Year Ended December 31,
	2017			2016			2015
Current:
Federal	$	—		$	—		$	—
State		4			3			1
Foreign		—			—			—
Total Current		4			3			1
Deferred:
Federal		—			—			—
State		—			—			—
Foreign		(497	)		(575	)		(302	)
Total Deferred		(497	)		(575	)		(302	)
Income tax (benefit) expense	$	(493	)	$	(572	)	$	(301	)

Components of Net Deferred Tax Assets and Liabilities

The components that comprise the Company’s net deferred tax assets at December 31, 2017 and 2016 consist of the following (in thousands):

	As of December 31,
	2017			2016
Deferred tax assets:
Stock compensation	$	73,336		$	87,239
Net operating loss carryforwards		42,784			37,507
Leases and other accrued liabilities		1,868			2,096
Tax credits		845			—
Accrued compensation		682			808
Total deferred tax assets		119,515			127,650
Deferred tax liabilities:
Foreign intangibles		(499	)		(996	)
Depreciation and amortization		(494	)		(309	)
Total deferred tax liabilities		(993	)		(1,305	)
Net deferred tax assets		118,522			126,345
Valuation allowance		(119,020	)		(127,341	)
Net deferred tax liability	$	(498	)	$	(996	)

Reconciliation of Federal Statutory Income Tax Rate

A reconciliation of the federal statutory income tax rate to the Company’s effective income tax rate is as follows:

	For the Year Ended December 31,
	2017				2016				2015
Tax computed at federal statutory rate		34.0		%		34.0		%		34.0		%
Section 382/383 NOL		—				8.6				(3.5	)
State income taxes, net of federal tax benefit		5.3				3.6				2.6
Tax rate adjustment		4.8				1.5				—
Tax Cuts and Jobs Act		(53.4	)			—				—
Research and development credits		0.6				1.3				0.1
Stock-based compensation		(0.3	)			(0.3	)			(0.4	)
Other		0.8				(0.5	)			(3.8	)
Valuation allowance		8.7				(47.7	)			(28.9	)
Effective income tax rate		0.5		%		0.5		%		0.1		%

Summarizes of Changes in Unrecognized Tax Benefits

The following table summarizes the changes to the amount of unrecognized tax benefits (in thousands):

Unrecognized tax benefits at December 31, 2015	$	1,203
Decrease for prior year tax positions		(1,203	)
Increase for prior year tax positions		2,578
Increase for current year tax positions		2,056
Unrecognized tax benefits at December 31, 2016		4,634
Decrease for prior year tax positions		(812	)
Increase for current year tax positions		2,755
Unrecognized tax benefits at December 31, 2017	$	6,577

Investment In Inex Bio, Inc (Tables)

12 Months Ended

Dec. 31, 2017

Summary of Purchase Price Paid to Inex Bio

The following summarizes the net consideration paid to Holdings (in thousands):

Consideration	Total
Cash	$	6,518
Fair value of warrants		22,747
Less cash paid to acquire shares in Inex Bio		(1,100	)
Net consideration	$	28,165

Summary of Assets and Liabilities Assumed

The following table summarizes the assets acquired and liabilities assumed (in thousands):

Cash	$	763
Intangible assets—reacquired rights of Company technology		8,636
Other assets		42
Investment in Inex Bio		(221	)
Deferred tax liability		(1,467	)
Accounts payable		(1	)
Total assets acquired and liabilities assumed	$	7,752

Inex Bio Inc

Summary of Purchase Price Paid to Inex Bio

The purchase price paid to acquire Inex Bio from the other owners is as follows (in thousands):

Consideration	Total
Cash paid by Inex Bio Holdings, LLC	$	1,100
Cash paid by Company		1,482
Fair value of warrants		5,170
Aggregate purchase price	$	7,752

Summarized Quarterly Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Summary of Quarterly Data (Unaudited)

The table below presents unaudited quarterly data for fiscal 2017 and 2016 (in thousands, except for share and per share amounts):

	1st Quarter			2nd Quarter			3rd Quarter			4th Quarter
2017
Revenue	$	11		$	14		$	8		$	12
Operating expenses		25,475			23,834			24,450			25,406
Operating loss		(25,464	)		(23,820	)		(24,442	)		(25,394	)
Net loss		(24,515	)		(23,452	)		(23,969	)		(24,487	)
Net loss per share - basic and diluted	$	(0.30	)	$	(0.29	)	$	(0.30	)	$	(0.31	)
Shares used in calculating net loss per share - basic and diluted		82,138,438			81,440,816			79,440,591			79,358,861

	1st Quarter			2nd Quarter			3rd Quarter			4th Quarter
2016
Revenue	$	6		$	12		$	12		$	14
Operating expenses		31,622			34,977			32,787			25,157
Operating loss		(31,616	)		(34,965	)		(32,775	)		(25,143	)
Net loss		(30,677	)		(33,997	)		(31,897	)		(24,238	)
Net loss per share - basic and diluted	$	(0.38	)	$	(0.41	)	$	(0.39	)	$	(0.29	)
Shares used in calculating net loss per share - basic and diluted		81,574,709			81,959,248			82,154,219			82,235,571

Description of Business and Basis of Presentation - Additional Information (Detail) $ / shares in Units, $ in Thousands		1 Months Ended	12 Months Ended
	Jul. 10, 2015	Jul. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($) shares
Description Of Business And Basis Of Presentation [Line Items]
Proceeds from sale of common stock		$ 221,500
Underwriting discounts, commissions and offering expenses		$ 16,800
Accumulated deficit			$ (498,713)	$ (387,063)
Net cash used in operating activities			$ (48,780)	$ (38,593)	$ (25,305)
Forward stock split of its outstanding common stock	1.8515
Common Stock
Description Of Business And Basis Of Presentation [Line Items]
Common stock sold \| shares					4,063,333
Forward stock split of its outstanding common stock	1.8515
Initial Public Offering
Description Of Business And Basis Of Presentation [Line Items]
Common stock price per share \| $ / shares		$ 25
Proceeds from sale of common stock		$ 221,500
Underwriting discounts, commissions and offering expenses		$ 16,800
Initial Public Offering \| Common Stock
Description Of Business And Basis Of Presentation [Line Items]
Common stock sold \| shares		9,531,200			9,531,200

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Nov. 30, 2015
Accounting Policies [Line Items]
Cash and cash equivalents original maturities	3 months
Maximum original maturity period of short-term marketable securities	12 months
Minimum original maturity period of long-term marketable securities	12 months
Other than temporary impairments for marketable securities	$ 0	$ 0	$ 0
Estimated useful lives of intangible assets	4 years
Impairment losses of long-lived assets	$ 0	0	0
Fair value inputs, transfers into or out of Level 1, 2 or 3 categories	0	0	$ 0
Accrued interest or penalties associated with uncertain tax positions	$ 0	$ 0
Total amount authorized for repurchase				$ 50,000,000
Minimum
Accounting Policies [Line Items]
Marketable securities original maturities	3 months
Minimum \| California
Accounting Policies [Line Items]
Tax year open for examination	2013
Minimum \| Federal
Accounting Policies [Line Items]
Tax year open for examination	2014
Maximum \| California
Accounting Policies [Line Items]
Tax year open for examination	2017
Maximum \| Federal
Accounting Policies [Line Items]
Tax year open for examination	2017
VIE \| Minimum
Accounting Policies [Line Items]
Percentage of ownership interest	20.00%
VIE \| Maximum
Accounting Policies [Line Items]
Percentage of ownership interest	50.00%

Summary of Significant Accounting Policies - Schedule of Estimated Useful Lives of Property, Plant and Equipment (Detail)	12 Months Ended
	Dec. 31, 2017
Buildings
Property Plant And Equipment [Line Items]
Property and equipment estimated useful lives	39 years
Software
Property Plant And Equipment [Line Items]
Property and equipment estimated useful lives	3 years
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property and equipment estimated useful lives	5 years
Furniture And Fixtures
Property Plant And Equipment [Line Items]
Property and equipment estimated useful lives	5 years
IT Equipment
Property Plant And Equipment [Line Items]
Property and equipment estimated useful lives	3 years
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment estimated useful lives, term	The lesser of the lease term or the life of the asset

Summary of Significant Accounting Policies - Securities Excluded from the Computation of Potentially Dilutive Securities (Detail) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	24,302,527	24,890,156	27,727,147
Employee Stock Option
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	5,693,250	6,307,386	8,777,893
Outstanding Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	888,189	814,456	1,129,638
Outstanding Warrants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	17,721,088	17,768,314	17,819,616

Summary of Significant Accounting Policies - Schedule of Revenue from Different Geographic Regions (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Revenue	$ 12	$ 8	$ 14	$ 11	$ 14	$ 12	$ 12	$ 6	$ 45	$ 44	$ 236
United States
Segment Reporting Information [Line Items]
Revenue									45	44	191
Europe
Segment Reporting Information [Line Items]
Revenue									0	0	21
Other non-U.S.
Segment Reporting Information [Line Items]
Revenue									$ 0	$ 0	$ 24

Financial Statement Details - Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financial Statement Details [Abstract]
Interest receivable - marketable securities	$ 764	$ 1,484
Prepaid license fees	597	462
Prepaid insurance	572	531
Equipment deposits	482	482
Prepaid services	416	1,191
Prepaid rent	373	360
Insurance claim receivable	340	0
Prepaid supplies	210	0
Prepaid legal fees	0	350
Other	398	275
Total prepaid expenses and other current assets	$ 4,152	$ 5,135

Financial Statement Details - Property, Plant and Equipment, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 81,029	$ 20,084
Accumulated depreciation	(4,303)	(1,178)
Property, plant and equipment, net	76,726	18,906
Construction in Progress
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	42,281	6,939
Buildings
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	23,811	4,348
Equipment
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	9,625	5,458
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	3,918	2,367
Software
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	1,092	769
Furniture And Fixtures
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 302	$ 203

Financial Statement Details - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financial Statement Details [Line Items]
Depreciation expense related to property, plant and equipment	$ 3,300,000	$ 1,000,000	$ 100,000
Property, plant and equipment, gross	81,029,000	20,084,000
Non cash build to suit lease asset	5,100,000
Amortization expense	2,300,000	2,600,000	1,300,000
Impairment loss on recognized investments	$ 0	0	$ 0
Technology License
Financial Statement Details [Line Items]
Remaining amortization period	1 year 3 months
Buildings
Financial Statement Details [Line Items]
Property, plant and equipment, gross	$ 23,811,000	$ 4,348,000
Capital Lease
Financial Statement Details [Line Items]
Property, plant and equipment, gross	19,500,000
Culver City California \| Financing Lease
Financial Statement Details [Line Items]
Property, plant and equipment, gross	$ 4,300,000

Financial Statement Details - Intangible Assets, Net (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Finite Lived Intangible Assets [Line Items]
Intangible assets, net	$ 2,826	$ 5,086
Technology License
Finite Lived Intangible Assets [Line Items]
Total intangible assets	9,042	9,042
Less accumulated amortization	(6,216)	(3,956)
Intangible assets, net	$ 2,826	$ 5,086

Financial Statement Details - Future Estimated Amortization Expense (Detail) - Technology License $ in Thousands	Dec. 31, 2017 USD ($)
Finite Lived Intangible Assets [Line Items]
2018	$ 2,261
2019	565
2020	0
2021	0
2022	0
Thereafter	0
Intangible assets, net	$ 2,826

Financial Statement Details - Other Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financial Statement Details [Abstract]
Restricted cash	$ 179	$ 179
Security deposit	127	137
Other	24	110
Equipment not placed in service	0	362
Other Assets Noncurrent	$ 330	$ 788

Financial Statement Details - Accrued Expenses (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financial Statement Details [Abstract]
Accrued construction costs	$ 6,212	$ 1,243
Accrued bonus	1,930	1,732
Accrued professional and service fees	1,048	1,008
Accrued compensation	944	898
Accrued preclinical and clinical trial costs	521	662
Other	612	321
Accrued Liabilities Current	$ 11,267	$ 5,864

Financial Statement Details - Other Current Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financial Statement Details [Abstract]
Deferred rent - current portion	$ 520	$ 197
Build-to-suit lease liability - current portion	334	281
Financing obligation - current portion	284	253
Other	235	160
Other current liabilities	$ 1,373	$ 891

Financial Statement Details - Investment Income, Net (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financial Statement Details [Abstract]
Interest income	$ 4,225	$ 5,168	$ 312
Investment amortization accretion expense, net	(1,597)	(2,182)	(38)
Dividend income	0	0	213
Net realized gains on investments	37	111	2,501
Investment income, net	$ 2,665	$ 3,097	$ 2,988

Cost Method Investment - Additional Information (Detail) - USD ($)	Dec. 31, 2017	Sep. 30, 2017	Mar. 31, 2017	Dec. 31, 2016
Schedule Of Cost Method Investments [Line Items]
Cost method investment	$ 8,500,000			$ 0
Viracta Therapeutics, Inc. \| Series B Convertible Preferred Stock
Schedule Of Cost Method Investments [Line Items]
Cost method investment		$ 0	$ 8,500,000
Viracta Therapeutics, Inc. \| Series B Convertible Preferred Stock \| Maximum
Schedule Of Cost Method Investments [Line Items]
Option to purchase additional shares under cost method investment		$ 8,500,000	$ 0

Cash Equivalents and Marketable Securities - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) Security	Dec. 31, 2016 USD ($)
Schedule Of Available For Sale Securities [Line Items]
Available for sale securities maturity period	3 years 8 months 12 days
Maximum
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale securities, period of unrealized loss positions	12 months	12 months
Corporate Debt Securities
Schedule Of Available For Sale Securities [Line Items]
Cash equivalent portions included in current fair values		$ 2.0
Debt Securities
Schedule Of Available For Sale Securities [Line Items]
Number of available-for-sale securities in unrealized loss positions \| Security	65
Foreign Government Bonds
Schedule Of Available For Sale Securities [Line Items]
Cash equivalent portions included in current fair values	$ 3.5

Cash Equivalents and Marketable Securities - Schedule of Cash Equivalents and Marketable Securities Available-for-Sale (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 137,759	$ 280,698
Unrealized Gains	5	134
Unrealized Losses	(386)	(418)
Fair Value	137,378	280,414
Current Assets
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	107,890	192,861
Unrealized Gains	5	61
Unrealized Losses	(117)	(79)
Fair Value	107,778	192,843
Current Assets \| Government Sponsored Securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	19,261
Unrealized Gains	0
Unrealized Losses	(28)
Fair Value	19,233
Current Assets \| Corporate Debt Securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	82,188	165,605
Unrealized Gains	5	40
Unrealized Losses	(84)	(76)
Fair Value	82,109	165,569
Current Assets \| Foreign Government Bonds
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	6,441	5,004
Unrealized Gains	0	0
Unrealized Losses	(5)	(2)
Fair Value	6,436	5,002
Current Assets \| Commercial Paper
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost		22,252
Unrealized Gains		21
Unrealized Losses		(1)
Fair Value		22,272
Noncurrent Assets
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	29,869	87,837
Unrealized Gains	0	73
Unrealized Losses	(269)	(339)
Fair Value	29,600	87,571
Noncurrent Assets \| Government Sponsored Securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	2,760	17,018
Unrealized Gains	0	2
Unrealized Losses	(43)	(38)
Fair Value	2,717	16,982
Noncurrent Assets \| Corporate Debt Securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	27,109	69,414
Unrealized Gains	0	71
Unrealized Losses	(226)	(290)
Fair Value	$ 26,883	69,195
Noncurrent Assets \| Foreign Government Bonds
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost		1,405
Unrealized Gains		0
Unrealized Losses		(11)
Fair Value		$ 1,394

Cash Equivalents and Marketable Securities - Available-for-Sale Investments in Unrealized Loss Position (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Schedule Of Available For Sale Securities [Line Items]
Available-for-Sale Investments, Less than 12 months, Estimated Fair Value	$ 78,808	$ 173,920
Available-for-Sale Investments, Less than 12 months, Gross Unrealized Losses	(124)	(418)
Available-for-Sale Investments, More than 12 months, Estimated Fair Value	49,519	0
Available-for-Sale Investments, More than 12 months, Gross Unrealized Losses	(262)	0
Government Sponsored Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-Sale Investments, Less than 12 months, Estimated Fair Value	9,744	17,204
Available-for-Sale Investments, Less than 12 months, Gross Unrealized Losses	(20)	(39)
Available-for-Sale Investments, More than 12 months, Estimated Fair Value	12,205	0
Available-for-Sale Investments, More than 12 months, Gross Unrealized Losses	(51)	0
Corporate Debt Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-Sale Investments, Less than 12 months, Estimated Fair Value	67,522	150,320
Available-for-Sale Investments, Less than 12 months, Gross Unrealized Losses	(104)	(366)
Available-for-Sale Investments, More than 12 months, Estimated Fair Value	35,918	0
Available-for-Sale Investments, More than 12 months, Gross Unrealized Losses	(206)	0
Foreign Government Bonds
Schedule Of Available For Sale Securities [Line Items]
Available-for-Sale Investments, Less than 12 months, Estimated Fair Value	1,542	6,396
Available-for-Sale Investments, Less than 12 months, Gross Unrealized Losses	0	(13)
Available-for-Sale Investments, More than 12 months, Estimated Fair Value	1,396	0
Available-for-Sale Investments, More than 12 months, Gross Unrealized Losses	$ (5)	$ 0

Cash Equivalents and Marketable Securities -Schedule of Realized Gains and Losses on Sales or Maturities of Available-for-Sale Securities (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash Equivalents And Marketable Securities [Abstract]
Available-for-sale Securities, Gross Realized Gains	$ 52	$ 190	$ 2,501
Available-for-sale Securities, Gross Realized Losses	(15)	(79)	0
Available-for-sale Securities, Net Realized Gains	$ 37	$ 111	$ 2,501

Collaboration and License Agreements - Additional Information (Detail)	1 Months Ended		12 Months Ended
	May 31, 2017 USD ($)	Feb. 28, 2010 USD ($)	Dec. 31, 2017 USD ($) Patient	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2004 USD ($)
Intrexon Corporation
Licensing Agreement [Line Items]
Milestone Payment Amount			$ 0	$ 0	$ 0
Milestone payments			0	0	0
License agreement term (years)		17 years
Agreement one time fee		$ 400,000
Fox Chase Cancer Center License Agreement
Licensing Agreement [Line Items]
Royalty expense earned or paid			0	0	100,000
Rush University Medical Center License Agreement
Licensing Agreement [Line Items]
Royalty expense earned or paid			25,000	25,000	25,000
Period of license agreement						12 years
Minimum annual royalty payment						$ 25,000
Payments in license agreement						2,500,000
Minimum sales milestone of license for first year						$ 300,000
Milestone payments			$ 0	0	0
First IND Filing \| Intrexon Corporation
Licensing Agreement [Line Items]
Milestone Payment Amount		100,000
First Phase II Clinical Trial \| Intrexon Corporation
Licensing Agreement [Line Items]
Milestone Payment Amount		100,000
First Phase III Clinical Trial \| Intrexon Corporation
Licensing Agreement [Line Items]
Milestone Payment Amount		400,000
Commercial Sale Related to Licensed Products \| Intrexon Corporation
Licensing Agreement [Line Items]
Milestone Payment Amount		$ 500,000
GSH-BSD
Licensing Agreement [Line Items]
License agreement termination notice period			60 days
Payments for initial license fees					$ 1,100,000
GSH \| Phase I glioblastoma study
Licensing Agreement [Line Items]
Milestone Payment Amount			$ 900,000	0
Viracta Therapeutics, Inc.
Licensing Agreement [Line Items]
License agreement termination notice period	90 days
Viracta Therapeutics, Inc. \| Minimum
Licensing Agreement [Line Items]
Milestone Payment Amount	$ 10,000,000
Viracta Therapeutics, Inc. \| Maximum
Licensing Agreement [Line Items]
Milestone Payment Amount	$ 25,000,000
Sorrento
Licensing Agreement [Line Items]
License agreement expiration period			2017-12
Altor
Licensing Agreement [Line Items]
Maximum number of patients in phase 1 and 2 for clinical trials \| Patient			400
Supplies and milestone charges for conducting clinical trials			$ 0	$ 0

Commitment and Contingencies - Additional Information (Detail)	1 Months Ended								12 Months Ended
	Jun. 30, 2017 USD ($)	Apr. 30, 2017 USD ($) ft²	Sep. 30, 2016 USD ($) ft²	Jun. 30, 2016 USD ($) ft² $ / ft²	Mar. 31, 2016 ft²	Nov. 30, 2015 USD ($) ft²	Jul. 31, 2015 USD ($) ft²	Jun. 30, 2015 USD ($) ft²	Dec. 31, 2017 USD ($) ft²	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Aug. 31, 2016 USD ($)	Sep. 30, 2015 USD ($)
Commitments And Contingencies [Line Items]
Liability accrued									$ 0
Non cash build to suit lease asset									5,100,000
Rent expense									$ 2,700,000	$ 2,700,000	$ 1,500,000
Woburn, Massachusetts
Commitments And Contingencies [Line Items]
Number of square foot of facility leased \| ft²				8,153	7,893
Period of agreement									In June 2016, the lease was amended to add 260 square feet, for a total of 8,153 square feet. The base rent, including the amendment, is $19,000 per month with a $1 per square foot annual increase on each anniversary date.
Term of lease arrangement					48 months
Lease commencement date					Apr. 29, 2016
Addition to number of square foot of facility leased \| ft²				260
Base rent - yearly				$ 19,000
Annual increase of base rent \| $ / ft²				1
Commitment; San Diego
Commitments And Contingencies [Line Items]
Base rent - monthly								$ 200,000
Number of square foot of facility leased \| ft²								44,700
Percentage of annual increase of base rent								3.00%
Base lease term								7 years
Sub Lease Agreements
Commitments And Contingencies [Line Items]
Number of square foot of facility leased \| ft²									8,500
Lease commencement date							Aug. 01, 2015
Base lease term							1 year
Rent expense							$ 0
Cardiff-by-the-Sea, California
Commitments And Contingencies [Line Items]
Base rent - monthly									$ 13,200
Number of square foot of facility leased \| ft²									2,550
Lease agreement extended lease period									Aug. 31, 2018
Doug St, LLC
Commitments And Contingencies [Line Items]
Base rent - monthly			$ 100,000
Period of agreement									The lease runs from July 2016 through July 2023. The Company has the option to extend the lease for an additional three year term through July 2026. The monthly rent is $0.1 million with annual increases of 3% beginning in July 2017.
Optional extended lease term			3 years
Percentage of annual increase of base rent			3.00%
Annual percentage increases to base rent commencement date			Jul. 31, 2017
Costs incurred									$ 30,000,000
Non cash build to suit lease asset									5,100,000
Property and equipment estimated useful lives			39 years
Doug St, LLC \| Research and Development
Commitments And Contingencies [Line Items]
Rent expense									$ 200,000	100,000
NantWorks
Commitments And Contingencies [Line Items]
Base rent - monthly						$ 47,000
Number of square foot of facility leased \| ft²						9,500
Period of agreement									The license was effective in May 2015 and extends through December 2020. The Company has the option to extend the license through December 2023. The monthly license fee is $47,000 with annual increases of 3% beginning in January 2017.
Percentage of annual increase of base rent						3.00%
Annual percentage increases to base rent commencement date						Jan. 31, 2017
Costs incurred												$ 3,500,000
Property and equipment estimated useful lives						39 years
Accumulated depreciation on building									$ 4,300,000
NantWorks \| Research and Development
Commitments And Contingencies [Line Items]
Rent expense									$ 200,000	$ 200,000	$ 200,000
El Segundo California \| Doug St, LLC
Commitments And Contingencies [Line Items]
Number of square foot of facility leased \| ft²			24,250
El Segundo California \| Agreement to Purchase Commercial Building
Commitments And Contingencies [Line Items]
Area of Land \| ft²		36,434
Escrow deposit		$ 5,000,000
Base rent - monthly		$ 0
Escrow closed period									2017-09
Remaining purchase price paid including closing costs									$ 15,300,000
Cary, North Carolina
Commitments And Contingencies [Line Items]
Number of square foot of facility leased \| ft²							3,067
Lease expiration date							Dec. 31, 2017
USPTO
Commitments And Contingencies [Line Items]
Attorney's fees and expert witness fees													$ 100,000
Award amount in favour to other party	$ 100,000
Prepaid Expenses and Current Assets
Commitments And Contingencies [Line Items]
Insurance receivable									$ 300,000

Commitment and Contingencies - Summary of Future Minimum Lease Payments (Detail) $ in Thousands	Dec. 31, 2017 USD ($)
Commitments And Contingencies Disclosure [Abstract]
2018	$ 4,094
2019	4,108
2020	4,056
2021	3,435
2022	3,538
Thereafter	2,056
Total minimum lease payments	$ 21,287

Related Party Agreements - Additional Information (Detail)		1 Months Ended						12 Months Ended
	Dec. 01, 2017 USD ($) ft²	Apr. 30, 2017 USD ($) ft²	Sep. 30, 2016 USD ($) ft²	Apr. 30, 2016 USD ($)	Mar. 31, 2016	Nov. 30, 2015 USD ($) ft²	Jun. 30, 2015	Dec. 31, 2017 USD ($) Officer	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Feb. 28, 2017 USD ($)	Aug. 31, 2016	Sep. 30, 2015 USD ($)
Related Party Transaction [Line Items]
Research and development								$ 42,044,000	$ 29,153,000	$ 11,434,000
Due to related parties								2,363,000	1,753,000
Prepaid expenses and other current assets								4,152,000	5,135,000
Selling, general and administrative								$ 57,121,000	95,391,000	227,678,000
Chan Soon-Shiong Institutes for Medicine (CSSIM) \| California
Related Party Transaction [Line Items]
Number of officers \| Officer								2
Research and development								$ 800,000
Due to related parties								$ 800,000
Tensorcom, Inc \| San Diego California
Related Party Transaction [Line Items]
Period of agreement								Initial lease from May 1, 2017 through April 30, 2018
Sublease termination notice period		30 days
Number of square foot of facility leased \| ft²		6,557
Base rent - monthly		$ 25,000
Percentage of annual increase of base rent		3.00%
Due between parties								$ 0
Tensorcom, Inc \| San Diego California \| Other Income
Related Party Transaction [Line Items]
Sublease revenue recognized								200,000
VivaBioCell S.p.A.
Related Party Transaction [Line Items]
Research and development								$ 600,000
Prepaid expenses and other current assets											$ 600,000
Doug St, LLC
Related Party Transaction [Line Items]
Period of agreement								The lease runs from July 2016 through July 2023. The Company has the option to extend the lease for an additional three year term through July 2026. The monthly rent is $0.1 million with annual increases of 3% beginning in July 2017.
Base rent - monthly			$ 100,000
Percentage of annual increase of base rent			3.00%
Due between parties								$ 0
Annual percentage increases to base rent commencement date			Jul. 31, 2017
Doug St, LLC \| Research and Development
Related Party Transaction [Line Items]
Rent expense								200,000	100,000
Doug St, LLC \| El Segundo California
Related Party Transaction [Line Items]
Number of square foot of facility leased \| ft²			24,250
Altor
Related Party Transaction [Line Items]
Percentage of ownership interest owned by CEO												20.00%
Supplies and milestone charges for conducting clinical trials								0	0
NantBioScience
Related Party Transaction [Line Items]
Research and development								600,000	$ 500,000
Due to related parties								$ 100,000
Sublease termination notice period	30 days
Number of square foot of facility leased \| ft²	1,965
Base rent - monthly	$ 10,000
Percentage of annual increase of base rent	3.00%
Sublease term	24 months
Initial term of agreement entered into with the related party by the entity					5 years
Research and development expense, ratable payment period								12 months	12 months
Prepayment of funding amount		$ 600,000		$ 600,000
NantBioScience \| Other Income
Related Party Transaction [Line Items]
Sublease revenue recognized								$ 10,000
NantWorks
Related Party Transaction [Line Items]
Due to related parties								1,500,000
Number of square foot of facility leased \| ft²						9,500
Base rent - monthly						$ 47,000
Percentage of annual increase of base rent						3.00%
Annual percentage increases to base rent commencement date						Jan. 31, 2017
NantWorks \| Shared Services Agreement
Related Party Transaction [Line Items]
Research and development								3,200,000	$ 2,100,000	300,000
Selling, general and administrative								3,600,000	3,900,000	1,800,000
NantWorks \| Reimbursements \| Shared Services Agreement
Related Party Transaction [Line Items]
Research and development								1,000,000	200,000
Selling, general and administrative								400,000	100,000
NantWorks \| Research and Development
Related Party Transaction [Line Items]
Rent expense								200,000	200,000	200,000
NantOmics
Related Party Transaction [Line Items]
Research and development								100,000	200,000	100,000
Due to related parties								100,000
Initial term of agreement entered into with the related party by the entity							5 years
Related party, agreement renewal term							1 year
NanoCav
Related Party Transaction [Line Items]
Research and development								0	100,000	0
Due between parties								0
Initial term of agreement entered into with the related party by the entity							5 years
Related party, agreement renewal term							1 year
Prepaid expenses for research and development													$ 45,000
NantCell Inc
Related Party Transaction [Line Items]
Research and development								300,000	$ 200,000	$ 0
Due to related parties								0
Prepaid expenses and other current assets								200,000
Initial term of agreement entered into with the related party by the entity							5 years
Related party, agreement renewal term							1 year
Related parties, capitalized equipment amount								$ 300,000

Spin-out of Brink Biologics and Coneksis - Additional Information (Detail) - Spinout - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Brink Biologics Inc
Related Party Transaction [Line Items]
Royalty revenue	$ 25,000	$ 21,000	$ 11,000
Number of days due for payment		30 days
Invoiced for services	100,000	$ 100,000	22,000
Amount owed to the company	34,000
Coneksis
Related Party Transaction [Line Items]
Number of days due for payment		30 days
Invoiced for services	40,000	$ 19,000	$ 6,000
Amount owed to the company	$ 100,000

Stockholders' Equity - Additional Information (Detail)				1 Months Ended									12 Months Ended
Stockholders' Equity - Additional Information (Detail)	Jul. 10, 2015	Jul. 08, 2015 USD ($) shares	Jun. 18, 2015 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Nov. 30, 2017 USD ($) $ / shares shares	Jun. 30, 2017 USD ($) $ / shares shares	May 31, 2017 USD ($) $ / shares shares	Mar. 31, 2017 USD ($) $ / shares shares	Jul. 31, 2015 USD ($) shares	Jun. 30, 2015 USD ($) shares	Apr. 30, 2015 USD ($) $ / shares shares	Mar. 31, 2015 $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) shares	Dec. 31, 2010 USD ($) $ / shares	Nov. 30, 2015 USD ($)	Dec. 31, 2014 shares
Class Of Stock [Line Items]
Total amount authorized for repurchase \| $																	$ 50,000,000
Repurchase of common stock, shares				316,827	244,574	1,744,009	1,028,200	300,000					3,633,610	2,157,944	0
Repurchase of common stock, value \| $													$ 15,227,000	$ 15,847,000	$ 4,798,000
Repurchase of common stock, par value \| $ / shares				$ 4.94	$ 4.87	$ 4.18	$ 3.92	$ 3.50					$ 4.16
Broker commissions on repurchases \| $													$ 100,000
Remained authorized shares for repurchase \| $				$ 19,100,000	$ 20,600,000	$ 21,800,000	$ 29,100,000	$ 33,100,000					$ 19,100,000
Forward stock split of its outstanding common stock	1.8515
Common stock, shares authorized				500,000,000						100,000,000			500,000,000	500,000,000
Proceeds from issuance of common stock net of issuance costs \| $		$ 7,000,000								$ 71,000,000
Common stock, shares issued				79,021,878					9,531,200				79,021,878	81,983,937
Proceeds from sale of common stock \| $									$ 221,500,000
Underwriting discounts, commissions and offering expenses \| $									16,800,000
Proceeds from exercise of warrants \| $													$ 61,000	$ 52,000	$ 7,348,000
Common stock, par value \| $ / shares				$ 0.0001									$ 0.0001	$ 0.0001
Common stock, shares outstanding				79,021,878									79,021,878	81,983,937
Common Stock Warrant
Class Of Stock [Line Items]
Derivative liability \| $											$ 1,500,000					$ 400,000
Inex Bio Inc
Class Of Stock [Line Items]
Warrants issued to purchase common shares												3,202,592
Stock price of warrants \| $ / shares												$ 2.00
Proceeds from exercise of warrants \| $											$ 6,400,000
Private Placement
Class Of Stock [Line Items]
Issuance of common stock, Shares										3,698,695
Proceeds from issuance of common stock net of issuance costs \| $									$ 17,000,000
Issuance costs \| $										$ 28,000
Common stock, shares issued		364,638							680,000
Common Class A
Class Of Stock [Line Items]
Repurchase of common stock, shares			249,952										0	0	249,952
Repurchase of common stock, value \| $			$ 4,800,000										$ 0	$ 0	$ 0
Repurchase of common stock, par value \| $ / shares			$ 19.20
Forward stock split of its outstanding common stock										1.00
Issuance of common stock, Shares															0
Common stock, shares issued				0									0	0	0			61,094,367
Common Class A \| Common Stock Warrant
Class Of Stock [Line Items]
Stock price of warrants \| $ / shares											$ 1.76
Warrant exercised and shares issued											114,822
Warrant exercisable price per share \| $ / shares																$ 2.44
Warrant expiration date																Feb. 29, 2020
Period of warrant holder protected against down-round financing after reverse merger																2 years
Percentage of shareholders consent																66.67%
Common Class A \| Private Placement
Class Of Stock [Line Items]
Issuance of common stock, Shares															0
Common Stock Class Undefined
Class Of Stock [Line Items]
Common stock, shares authorized																		80,000,000
Minimum
Class Of Stock [Line Items]
Repurchase of common stock, par value \| $ / shares													$ 3.10
Common stock, shares authorized									100,000,000
Maximum
Class Of Stock [Line Items]
Repurchase of common stock, par value \| $ / shares													$ 5.00
Common stock, shares authorized									500,000,000

Stockholders' Equity - Summary of Common Stock Repurchases (Detail) - USD ($)	1 Months Ended					12 Months Ended
	Dec. 31, 2017	Nov. 30, 2017	Jun. 30, 2017	May 31, 2017	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Equity [Abstract]
Total number of shares purchased	316,827	244,574	1,744,009	1,028,200	300,000	3,633,610	2,157,944	0
Average price paid per share	$ 4.94	$ 4.87	$ 4.18	$ 3.92	$ 3.50	$ 4.16
Total number of shares purchased as part of publicly announced plans or programs	3,633,610	3,316,783	3,072,209	1,328,200	300,000
Maximum approximate dollar value of shares that may yet be purchased under the plans or programs	$ 19,100,000	$ 20,600,000	$ 21,800,000	$ 29,100,000	$ 33,100,000	$ 19,100,000

Stockholders' Equity - Summary of Common Shares Reserved for Issuance (Detail)	Dec. 31, 2017 shares
Class Of Stock [Line Items]
Total shares reserved for future issuance	24,302,527
Issued and Outstanding Stock Options
Class Of Stock [Line Items]
Total shares reserved for future issuance	5,693,250
Issued and Outstanding Restricted Stock Units
Class Of Stock [Line Items]
Total shares reserved for future issuance	888,189
Outstanding Financing Warrants
Class Of Stock [Line Items]
Total shares reserved for future issuance	131,838
Outstanding Officer Warrants
Class Of Stock [Line Items]
Total shares reserved for future issuance	17,589,250

Stock-Based Compensation - Additional Information (Detail) $ / shares in Units, $ in Thousands				1 Months Ended			3 Months Ended	12 Months Ended
	Jul. 10, 2015	May 08, 2015 USD ($) $ / shares shares	Mar. 24, 2015 $ / shares shares	Jul. 31, 2015 shares	Jun. 30, 2015	Mar. 31, 2014 shares	Jun. 30, 2015 USD ($)	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance \| shares										4,249,857
Forward stock split of its outstanding common stock	1.8515
Cash received from exercised options								$ 1,154	$ 1,373	$ 878
Stock-based compensation expense								36,997	73,852	211,221
Outstanding Warrants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation cost related to non-vested stock options								$ 17,800
Weighted-average period for recognition								7 months 6 days
Officer
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share Based Compensation Arrangement By Share Based Payment Award Award Vesting Period1								7 months 6 days
Incremental compensation cost										91,500
Incremental compensation expense								$ 12,000	$ 19,000	$ 53,800
Remaining incremental compensation expense								$ 6,700
Forward stock split of its outstanding common stock								1
Officer \| Vest over a 40-month service period beginning on April 1, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement, Award Vesting Rights, Percentage				50.00%
Officer \| Vest based on the achievement of various milestones
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement, Award Vesting Rights, Percentage								50.00%
Officer \| Non Qualified Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation, expiration period		4 years	10 years
Number of shares granted \| shares			1,851,500
Shares granted at an exercise price \| $ / shares		$ 2.20	$ 2.00
Share Based Compensation Arrangement By Share Based Payment Award Award Vesting Period1			40 months
Officer \| Outstanding Warrants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation, expiration period		4 years
Common Class A
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Forward stock split of its outstanding common stock					1.00
2015 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance \| shares								2,659,117		3,500,000
Additional Shares that may be added to shares reserved for issuance \| shares								6,635,489
Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares granted \| shares										5,713,899
Shares granted at an exercise price \| $ / shares										$ 7.92
Stock option outstanding \| shares								5,693,250	6,307,386	8,777,893	5,138,410
Shares outstanding at an exercise price \| $ / shares								$ 7.71	$ 7.14	$ 5.36	$ 0.85
Stock options, vested and exercisable \| shares								5,114,656	5,210,756	4,844,857
Aggregate intrinsic value of stock options exercised								$ 1,700	$ 17,000	$ 2,400
Cash received from exercised options								1,200	1,400	900
Stock-based compensation expense								4,267	$ 14,720	$ 25,498
Unrecognized compensation cost related to non-vested stock options								$ 4,800
Weighted-average period for recognition								1 year 2 months 12 days
Employee Stock Option \| Officer
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option outstanding \| shares								1,455,450
Shares outstanding at an exercise price \| $ / shares								$ 25.00
Employee Stock Option \| 2014 Equity Incentive Plan \| Common Class A
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance \| shares						11,109,000
Share-based compensation, expiration period						10 years
Performance Shares \| Officer
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock price of warrants \| $ / shares			$ 2.00
Incremental compensation cost		$ 53,000
Performance Shares \| Officer \| Outstanding Warrants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation, expiration period			3 years
Number of shares granted \| shares		10,183,250	17,589,250
Service \| Officer
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Incremental compensation cost							$ 38,500
Service \| Officer \| Outstanding Warrants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares granted \| shares		7,406,000
Outstanding Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares granted \| shares								615,983	407,800	1,614,788
Stock-based compensation expense								$ 894	$ 8,166	$ 17,505
Weighted-average period for recognition								2 years 9 months 18 days
Unrecognized compensation cost related to non-vested stock options								$ 4,100
Outstanding Restricted Stock Units \| Officer
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares granted \| shares				970,300
Non Employee Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares granted to employee \| shares								0	0	231,437
Option exercise period										90 days
Stock-based compensation expense								$ 0	$ 0	$ 3,300
Non Employee Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares granted \| shares								77,250	67,500	353,188
Stock-based compensation expense								$ 252	$ 464	$ 270
Weighted-average period for recognition								2 years 4 months 24 days
Unrecognized compensation cost related to non-vested stock options								$ 900
Employee Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average period for recognition								2 years 10 months 24 days
Unrecognized compensation cost related to non-vested stock options								$ 3,100
Employee Restricted Stock Units \| Outside Consultant
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares granted \| shares								27,250

Stock-Based Compensation - Stock Based Compensation Expenses Related to Statement of Operations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 36,997	$ 73,852	$ 211,221
Warrants For Common Stock \| Officer
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	31,584	50,502	141,901
Warrants For Common Stock \| Former Director Related to Inex Bio, Inc
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	0	0	22,747
Employee Stock Option
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	4,267	14,720	25,498
Non Employee Stock Options
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	0	0	3,300
Employee Restricted Stock Units
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	894	8,166	17,505
Non Employee Restricted Stock Units
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	252	464	270
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	102	852	1,221
Selling, General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 36,895	$ 73,000	$ 210,000

Stock-Based Compensation - Stock Option Activity (Detail) - Employee Stock Option - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Number of Shares
Stock Options, Beginning Balance	6,307,386	8,777,893	5,138,410
Stock Options, Options granted			5,713,899
Stock Options, Options exercised	(614,136)	(2,398,883)	(1,127,105)
Stock Options, Options forfeited/canceled		(71,624)	(947,311)
Stock Options, Ending Balance	5,693,250	6,307,386	8,777,893	5,138,410
Stock Options, Vested and Exercisable	5,114,656	5,210,756	4,844,857
Weighted Average Exercise Price
Weighted Average Exercise Price, Outstanding Beginning balance	$ 7.14	$ 5.36	$ 0.85
Weighted Average Exercise Price, Options granted			7.92
Weighted Average Exercise Price, Options exercised	1.88	0.76	0.86
Weighted Average Exercise Price, Options forfeited/canceled		2.00	1.87
Weighted Average Exercise Price, Outstanding Ending balance	7.71	$ 7.14	$ 5.36	$ 0.85
Weighted Average Exercise Price, Vested and Exercisable	$ 8.33
Aggregate Intrinsic Value
Aggregate Intrinsic Value, Outstanding, Beginning balance	$ 19,100	$ 116,273	$ 5,298
Aggregate Intrinsic Value, Outstanding, Ending balance	11,920	$ 19,100	$ 116,273	$ 5,298
Aggregate Intrinsic Value, Vested and Exercisable	$ 10,073
Weighted Average Remaining Contractual Life
Weighted Average Remaining Contractual Life, Outstanding	5 years 3 months 18 days	6 years 4 months 24 days	7 years 2 months 12 days	9 years 8 months 12 days
Weighted Average Remaining Contractual Life, Vested and Exercisable	5 years 8 months 12 days

Stock-Based Compensation - Summary of Options Outstanding and Vested Pricing of Exercise Prices (Detail) - Employee Stock Option	12 Months Ended
	Dec. 31, 2017 $ / shares shares
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Options Outstanding, Number Outstanding	5,693,250
Options Outstanding, Weighted-Average Life (in Years)	5 years 3 months 18 days
Options Outstanding, Number Exercisable	5,114,656
Options Outstanding, Weighted- Average Life (in years)	5 years 8 months 12 days
$0.22
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices \| $ / shares	$ 0.22
Options Outstanding, Number Outstanding	134,800
Options Outstanding, Weighted-Average Life (in Years)	6 years 2 months 12 days
Options Outstanding, Number Exercisable	134,800
Options Outstanding, Weighted- Average Life (in years)	6 years 2 months 12 days
$0.42
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices \| $ / shares	$ 0.42
Options Outstanding, Number Outstanding	589,660
Options Outstanding, Weighted-Average Life (in Years)	6 years 10 months 24 days
Options Outstanding, Number Exercisable	589,660
Options Outstanding, Weighted- Average Life (in years)	6 years 10 months 24 days
$1.76
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices \| $ / shares	$ 1.76
Options Outstanding, Number Outstanding	699,060
Options Outstanding, Weighted-Average Life (in Years)	7 years
Options Outstanding, Number Exercisable	699,060
Options Outstanding, Weighted- Average Life (in years)	7 years
$2.00
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices \| $ / shares	$ 2.00
Options Outstanding, Number Outstanding	962,780
Options Outstanding, Weighted-Average Life (in Years)	7 years 1 month 6 days
Options Outstanding, Number Exercisable	962,780
Options Outstanding, Weighted- Average Life (in years)	7 years 1 month 6 days
$2.20
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices \| $ / shares	$ 2.20
Options Outstanding, Number Outstanding	1,851,500
Options Outstanding, Weighted-Average Life (in Years)	1 year 2 months 12 days
Options Outstanding, Number Exercisable	1,272,906
Options Outstanding, Weighted- Average Life (in years)	1 year 2 months 12 days
$ 25.00
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Prices \| $ / shares	$ 25.00
Options Outstanding, Number Outstanding	1,455,450
Options Outstanding, Weighted-Average Life (in Years)	7 years 7 months 6 days
Options Outstanding, Number Exercisable	1,455,450
Options Outstanding, Weighted- Average Life (in years)	7 years 7 months 6 days

Stock-Based Compensation - Black-Scholes Option-Pricing Model to Determine Fair Value of Assumptions Used for Employee Grants and Non-Employee Grants Stock Options (Detail)	12 Months Ended
	Dec. 31, 2015 $ / shares
Employee Grants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate, minimum	1.50%
Risk-free interest rate, maximum	1.80%
Expected volatility	80.00%
Dividend yield	0.00%
Weighted-average measurement date fair value	$ 12.08
Employee Grants \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	4 years
Employee Grants \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	5 years 6 months
Non Employee Grants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate, minimum	0.00%
Risk-free interest rate, maximum	2.40%
Expected volatility	80.00%
Dividend yield	0.00%
Weighted-average measurement date fair value	$ 15.25
Non Employee Grants \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	8 years 4 months 24 days
Non Employee Grants \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	9 years 10 months 24 days

Stock-Based Compensation - Restricted Stock Units (RSUs) Activity (Detail) - Outstanding Restricted Stock Units - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Unvested, Beginning balance	814,456	1,129,638	0
Number of Shares, Granted	615,983	407,800	1,614,788
Number of Shares, Vested	(244,209)	(537,982)	(485,150)
Number of Shares, Forfeited/Canceled	(298,041)	(185,000)
Number of Shares, Unvested, Ending balance	888,189	814,456	1,129,638
Weighted-Average Grant Date Fair Value, Unvested, beginning balance	$ 13.98	$ 20.51	$ 0
Weighted-Average Grant Date Fair Value, Granted	4.50	7.76	21.86
Weighted-Average Grant Date Fair Value, Vested	15.82	23.75	25.00
Weighted-Average Grant Date Fair Value, Forfeited/Canceled	10.28	11.75
Weighted-Average Grant Date Fair Value, Unvested, ending balance	$ 8.14	$ 13.98	$ 20.51

Stock-Based Compensation - Summary of Warrant Activity (Detail) - Outstanding Warrants - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Warrant [Line Items]
Warrants, Beginning Balance	17,768,314	17,819,616	1,850,937
Warrants granted			20,791,842
Warrants exercised	(47,226)	(51,302)	(4,677,101)
Warrants forfeited			(146,062)
Warrants, Ending Balance	17,721,088	17,768,314	17,819,616
Warrants, Vested and exercisable Ending Balance	16,425,038

Stock-Based Compensation - Reserved Authorized Shares of Common Stock for Future Grants of Equity Awards (Detail) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jul. 31, 2015
Common Stock Reserved For Future Issuance [Line Items]
Total shares authorized			4,249,857
2015 Equity Incentive Plan
Common Stock Reserved For Future Issuance [Line Items]
Total shares authorized	2,659,117		3,500,000
Shares reserved for future grants, Beginning balance	2,745,028	2,126,682
Grants	(615,983)	(407,800)	(3,070,238)
Forfeitures added back to available pool	298,041	185,000	947,063
Net share settlement	232,031	225,754
Exercised option shares repurchased		615,392
Shares reserved for future grants, Ending balance	2,659,117	2,745,028	2,126,682
2014 Equity Incentive Plan
Common Stock Reserved For Future Issuance [Line Items]
Shares remaining from 2014 Equity Incentive Plan				749,857

Income Taxes - Summary of Loss Before Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
U.S. loss before taxes	$ (94,734)	$ (118,743)	$ (235,750)
Foreign loss before taxes	(2,182)	(2,638)	(1,427)
Loss before income taxes	$ (96,916)	$ (121,381)	$ (237,177)

Income Taxes - Summary of Income Tax (Benefit) Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
Federal	$ 0	$ 0	$ 0
State	4	3	1
Foreign	0	0	0
Total Current	4	3	1
Deferred:
Federal	0	0	0
State	0	0	0
Foreign	(497)	(575)	(302)
Total Deferred	(497)	(575)	(302)
Income tax (benefit) expense	$ (493)	$ (572)	$ (301)

Income Taxes - Components of Net Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Stock compensation	$ 73,336	$ 87,239
Net operating loss carryforwards	42,784	37,507
Leases and other accrued liabilities	1,868	2,096
Tax credits	845	0
Accrued compensation	682	808
Total deferred tax assets	119,515	127,650
Deferred tax liabilities:
Foreign intangibles	(499)	(996)
Depreciation and amortization	(494)	(309)
Total deferred tax liabilities	(993)	(1,305)
Net deferred tax assets	118,522	126,345
Valuation allowance	(119,020)	(127,341)
Net deferred tax liability	$ (498)	$ (996)

Income Taxes - Reconciliation of Federal Statutory Income Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Tax computed at federal statutory rate	34.00%	34.00%	34.00%
Section 382/383 NOL	0.00%	8.60%	(3.50%)
State income taxes, net of federal tax benefit	5.30%	3.60%	2.60%
Tax rate adjustment	4.80%	1.50%	0.00%
Tax Cuts and Jobs Act	(53.40%)	0.00%	0.00%
Research and development credits	0.60%	1.30%	0.10%
Stock-based compensation	(0.30%)	(0.30%)	(0.40%)
Other	0.80%	(0.50%)	(3.80%)
Valuation allowance	8.70%	(47.70%)	(28.90%)
Effective income tax rate	0.50%	0.50%	0.10%

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax [Line Items]
Cumulative change in ownership		50.00%
Period of cumulative ownership change		3 years
Derecognized deferred tax assets		$ 800,000	$ 1,200,000
Tax computed at federal statutory rate		34.00%	34.00%	34.00%
Reduction in deferred tax asset balance		$ 51,700,000
Deferred tax expense (benefit)		0
Deferred tax assets valuation allowance		119,020,000	$ 127,341,000
Deferred tax assets change in valuation allowance		8,300,000
Tax benefits credited to contributed capital		200,000
Unrecognized tax benefits that would not impact effective tax rate		6,000,000
California \| Research Tax Credits
Income Tax [Line Items]
Tax credit carryforwards		1,900,000
Federal
Income Tax [Line Items]
Net operating loss carryforwards		$ 165,900,000
Net operating loss carryforwards expiration date		2024
Federal \| Research Tax Credits
Income Tax [Line Items]
Tax credit carryforwards		$ 3,200,000
Tax credit carryforward expiration period		2034
State
Income Tax [Line Items]
Net operating loss carryforwards		$ 136,200,000
Net operating loss carryforwards expiration date		2030
State \| Research Tax Credits
Income Tax [Line Items]
Tax credit carryforward expiration period		2029
Foreign
Income Tax [Line Items]
Net operating loss carryforwards		$ 200,000
Net operating loss carryforwards expiration date		2022
Maximum
Income Tax [Line Items]
Tax computed at federal statutory rate		35.00%
Maximum \| California
Income Tax [Line Items]
Tax year open for examination		2017
Maximum \| Federal
Income Tax [Line Items]
Tax year open for examination		2017
Minimum \| California
Income Tax [Line Items]
Tax year open for examination		2013
Minimum \| Federal
Income Tax [Line Items]
Tax year open for examination		2014
Scenario Plan
Income Tax [Line Items]
Tax computed at federal statutory rate	21.00%

Income Taxes - Summarizes of Changes in Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Unrecognized tax benefits at beginning balance	$ 4,634	$ 1,203
Decrease for prior year tax positions	(812)	(1,203)
Increase for prior year tax positions		2,578
Increase for current year tax positions	2,755	2,056
Unrecognized tax benefits at ending balance	$ 6,577	$ 4,634

Notes Payable - Additional Information (Detail) - USD ($)	1 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2007
Debt Instrument [Line Items]
Payments on notes payable	$ 130,000	$ 0	$ 0	$ 132,000
2007 Settlement Agreement Note
Debt Instrument [Line Items]
Notes payable				$ 0	$ 300,000
2007 Settlement Agreement Note \| 2015 Supplemental Agreement
Debt Instrument [Line Items]
Notes payable		$ 0
Difference amount of notes payable and amount paid to retire	$ 130,000
Common Class A \| 2007 Settlement Agreement Note with 2015 Supplemental Agreement
Debt Instrument [Line Items]
Common stock exercise of warrants purchase of share	32,675
Common stock exercise of warrants purchase price per share	$ 2.44
Common Class A \| 2009 Convertible Notes
Debt Instrument [Line Items]
Conversion price of common stock				$ 2.44	$ 0

Investment in Inex Bio, Inc - Additional Information (Detail) - USD ($)		1 Months Ended			2 Months Ended	12 Months Ended
	Mar. 30, 2015	Apr. 30, 2015	May 31, 2012	Apr. 30, 2012	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Asset Purchase [Line Items]
Number of shares acquired during period			57,000
Stock issued during period, value, acquisitions			$ 200,000
Outstanding shares acquired, percentage			22.20%
Percentage of fully diluted shares acquired			17.40%
Proceeds from exercise of warrants						$ 61,000	$ 52,000	$ 7,348,000
Stock-based compensation expense						36,997,000	$ 73,852,000	211,221,000
Inex Bio Holdings, LLC
Asset Purchase [Line Items]
Payments to acquire business						6,500,000
Stock price of warrants	$ 10.72
Term of warrants after closing date of the purchase agreement	14 days
Expected volatility rate	80.00%
Issuance of warrants in Inex Bio acquisition						22,747,000
Stock-based compensation expense						22,700,000
Cash based compensation						$ 5,400,000
Inex Bio Holdings, LLC \| Common Class A
Asset Purchase [Line Items]
Warrants issued to acquire shares						2,609,520
Common stock exercise price						$ 2.00
Proceeds from exercise of warrants		$ 5,200,000
Other Owner Of Inex Bio Inc
Asset Purchase [Line Items]
Payments to acquire business	$ 1,500,000
Stock price of warrants	$ 10.72
Term of warrants after closing date of the purchase agreement	14 days
Expected volatility rate	80.00%
Issuance of warrants in Inex Bio acquisition						$ 5,170,000
Other Owner Of Inex Bio Inc \| Common Class A
Asset Purchase [Line Items]
Warrants issued to acquire shares	593,072
Common stock exercise price	$ 2.00
Proceeds from exercise of warrants		$ 1,200,000
Inex Bio
Asset Purchase [Line Items]
Intangible assets amortizes period						4 years
Cambridge Equities, L.P \| Inex Bio Holdings, LLC
Asset Purchase [Line Items]
Ownership percentage of third party business					50.00%
Eragon Ventures, LLC
Asset Purchase [Line Items]
Number of shares acquired during period					220,000
Ownership percentage of third party business					50.00%
Percentage shares acquired					67.30%
Payments to acquire business					$ 1,100,000
Inex license agreement
Asset Purchase [Line Items]
Milestone payment amount								$ 0	$ 0	$ 0
Percentage of royalty on net sales				5.00%
Up front fee \| Inex license agreement
Asset Purchase [Line Items]
License fees received				$ 300,000
Maximum \| Inex license agreement
Asset Purchase [Line Items]
Milestone payment amount				$ 800,000

Investment in Inex Bio, Inc - Summary of Purchase Price Paid to Inex Bio (Detail) - Other Owner Of Inex Bio Inc $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)
Asset Purchase [Line Items]
Cash paid by Inex Bio Holdings, LLC	$ 1,100
Cash paid by Company	1,482
Fair value of warrants	5,170
Aggregate purchase price	$ 7,752

Investment in Inex Bio, Inc - Summary of Assets and Liabilities Assumed (Detail) - Other Owner Of Inex Bio Inc $ in Thousands	Dec. 31, 2017 USD ($)
Asset Purchase [Line Items]
Cash	$ 763
Intangible assets—reacquired rights of Company technology	8,636
Other assets	42
Investment in Inex Bio	(221)
Deferred tax liability	(1,467)
Accounts payable	(1)
Total assets acquired and liabilities assumed	$ 7,752

Investment in Inex Bio, Inc - Summary of Net Consideration Paid to Holdings (Detail) - Inex Bio Holdings, LLC $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)
Asset Purchase [Line Items]
Cash	$ 6,518
Fair value of warrants	22,747
Less cash paid to acquire shares in Inex Bio	(1,100)
Aggregate purchase price	$ 28,165

Summary of Quarterly Data (Unaudited) (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Data [Abstract]
Revenue	$ 12	$ 8	$ 14	$ 11	$ 14	$ 12	$ 12	$ 6	$ 45	$ 44	$ 236
Operating expenses	25,406	24,450	23,834	25,475	25,157	32,787	34,977	31,622	99,165	124,544	239,112
Operating loss	(25,394)	(24,442)	(23,820)	(25,464)	(25,143)	(32,775)	(34,965)	(31,616)	(99,120)	(124,500)	(238,876)
Net loss	$ (24,487)	$ (23,969)	$ (23,452)	$ (24,515)	$ (24,238)	$ (31,897)	$ (33,997)	$ (30,677)	$ (96,423)	$ (120,809)	$ (236,876)
Net loss per share - basic and diluted	$ (0.31)	$ (0.30)	$ (0.29)	$ (0.30)	$ (0.29)	$ (0.39)	$ (0.41)	$ (0.38)	$ (1.20)	$ (1.47)	$ (3.31)
Shares used in calculating net loss per share - basic and diluted	79,358,861	79,440,591	81,440,816	82,138,438	82,235,571	82,154,219	81,959,248	81,574,709	80,583,910	81,979,005	71,519,609

Employee Benefits - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
401(k) Plan
Defined Contribution Plan Disclosure [Line Items]
Employee benefit plan, company contributions	$ 400,000	$ 200,000	$ 4,000

Subsequent Event - Additional Information (Detail) - Chan Soon-Shiong Institutes for Medicine (CSSIM) - Subsequent Event	1 Months Ended
	Jan. 31, 2018 USD ($) Agreement Trial
Subsequent Event [Line Items]
Number of new agreements executed \| Agreement	2
Number of clinical trials \| Trial	2
Maximum
Subsequent Event [Line Items]
Cost of clinical trials \| $	$ 12,700,000

Fair Value Measurements - Summary of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	$ 157,752	$ 286,492
Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	20,374	6,078
Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	137,378	280,414
Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	0	0
Current Assets \| Foreign Government Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	2,938	5,002
Current Assets \| Government Sponsored Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	19,233	22,272
Current Assets \| Cash and cash equivalents
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	23,872	8,083
Current Assets \| Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	82,109	163,564
Current Assets \| Level 1 \| Foreign Government Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	0	0
Current Assets \| Level 1 \| Government Sponsored Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	0	0
Current Assets \| Level 1 \| Cash and cash equivalents
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	20,374	6,078
Current Assets \| Level 1 \| Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	0	0
Current Assets \| Level 2 \| Foreign Government Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	2,938	5,002
Current Assets \| Level 2 \| Government Sponsored Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	19,233	22,272
Current Assets \| Level 2 \| Cash and cash equivalents
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	3,498	2,005
Current Assets \| Level 2 \| Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	82,109	163,564
Current Assets \| Level 3 \| Foreign Government Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	0	0
Current Assets \| Level 3 \| Government Sponsored Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	0	0
Current Assets \| Level 3 \| Cash and cash equivalents
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	0	0
Current Assets \| Level 3 \| Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	0	0
Noncurrent Assets \| Foreign Government Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value		1,394
Noncurrent Assets \| Government Sponsored Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	2,717	16,982
Noncurrent Assets \| Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	26,883	69,195
Noncurrent Assets \| Level 1 \| Foreign Government Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value		0
Noncurrent Assets \| Level 1 \| Government Sponsored Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	0	0
Noncurrent Assets \| Level 1 \| Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	0	0
Noncurrent Assets \| Level 2 \| Foreign Government Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value		1,394
Noncurrent Assets \| Level 2 \| Government Sponsored Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	2,717	16,982
Noncurrent Assets \| Level 2 \| Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	26,883	69,195
Noncurrent Assets \| Level 3 \| Foreign Government Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value		0
Noncurrent Assets \| Level 3 \| Government Sponsored Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	0	0
Noncurrent Assets \| Level 3 \| Corporate Debt Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	$ 0	$ 0