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Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2019	Oct. 31, 2019
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Trading Symbol	FGEN
Entity Registrant Name	FIBROGEN INC
Entity Central Index Key	0000921299
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Title of 12(b) Security	Common Stock, $0.01 par value
Security Exchange Name	NASDAQ
Entity File Number	1-36740
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	77-0357827
Entity Address, Address Line One	409 Illinois Street
Entity Address, City or Town	San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94158
City Area Code	415
Local Phone Number	978-1200
Document Quarterly Report	true
Document Transition Report	false
Entity Common Stock Shares Outstanding		87,250,064

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 196,592	$ 89,258
Short-term investments	432,040	532,144
Accounts receivable ($17,662 and $47,210 from a related party)	19,225	63,684
Inventories	4,908	0
Prepaid expenses and other current assets ($126,012 and $0 from a related party)	133,715	4,929
Total current assets	786,480	690,015
Restricted time deposits	4,145	4,145
Long-term investments	10,999	55,820
Property and equipment, net	43,208	127,198
Finance lease right-of-use assets	42,064	0
Other assets	7,068	3,420
Total assets	893,964	880,598
Current liabilities:
Accounts payable ($730 and $0 to a related party)	4,055	9,139
Accrued and other current liabilities ($954 and $444 to a related party)	70,825	66,123
Deferred revenue	257	13,771
Finance lease liabilities, current	12,149	0
Total current liabilities	87,286	89,033
Long-term portion of lease obligations	1,242	97,157
Product development obligations	16,256	16,798
Deferred rent	0	3,038
Deferred revenue, net of current	98,708	136,109
Finance lease liabilities, non-current	40,713	0
Other long-term liabilities	36,041	9,993
Total liabilities	280,246	352,128
Commitments and Contingencies
Stockholders’ equity:
Preferred stock, $0.01 par value; 125,000 shares authorized; no shares issued and outstanding at September 30, 2019 and December 31, 2018	0	0
Common stock, $0.01 par value; 225,000 shares authorized at September 30, 2019 and December 31, 2018; 87,211 and 85,432 shares issued and outstanding at September 30, 2019 and December 31, 2018	872	854
Additional paid-in capital	1,280,396	1,226,453
Accumulated other comprehensive loss	(224)	(2,281)
Accumulated deficit	(686,597)	(715,827)
Total stockholders’ equity	594,447	509,199
Non-controlling interests	19,271	19,271
Total equity	613,718	528,470
Total liabilities, stockholders’ equity and non-controlling interests	$ 893,964	$ 880,598

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Accounts receivable from related party	$ 17,662,000	$ 47,210,000
Prepaid expenses and other current assets from related party	126,012,000	0
Accounts payable to related party	730,000	0
Accrued and other current liabilities to related party	$ 954,000	$ 444,000
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	125,000,000	125,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	225,000,000	225,000,000
Common stock, shares issued	87,211,000	85,432,000
Common stock, shares outstanding	87,211,000	85,432,000

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenue:
Total revenue	$ 33,174	$ 29,027	$ 248,603	$ 104,903
Operating costs and expenses:
Cost of goods sold	$ 242	$ 0	$ 242	$ 0
Cost, Product and Service [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember
Research and development	$ 49,963	$ 56,443	$ 152,467	$ 165,555
Selling, general and administrative	35,823	15,356	84,772	45,961
Total operating costs and expenses	86,028	71,799	237,481	211,516
Income (loss) from operations	(52,854)	(42,772)	11,122	(106,613)
Interest and other, net
Interest expense	(702)	(2,739)	(2,209)	(8,257)
Interest income and other, net	4,193	3,079	12,496	7,796
Total interest and other, net	3,491	340	10,287	(461)
Income (loss) before income taxes	(49,363)	(42,432)	21,409	(107,074)
Provision for income taxes	76	124	256	299
Net income (loss)	$ (49,439)	$ (42,556)	$ 21,153	$ (107,373)
Net income (loss) per share:
Basic	$ (0.57)	$ (0.50)	$ 0.24	$ (1.28)
Diluted	$ (0.57)	$ (0.50)	$ 0.23	$ (1.28)
Weighted average number of common shares used to calculate net income (loss) per share:
Basic	87,007	84,508	86,390	83,713
Diluted	87,007	84,508	91,995	83,713
License Revenue [Member]
Revenue:
Total revenue	$ 11,935	$ 0	$ 162,517	$ 14,323
Development and Other Revenue [Member]
Revenue:
Total revenue	20,660	29,027	85,507	90,580
Product Revenue [Member]
Revenue:
Total revenue	$ 579	$ 0	$ 579	$ 0

Condensed Consolidated Statements of Operations (Unaudited) (Parenthetical) - Astellas Agreement [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Collaboration services and other revenue from a related party	$ 3,533	$ 5,131	$ 25,615	$ 16,448
License and milestone revenue from a related party	$ 11,935	$ 0	$ 129,405	$ 14,323

Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ (49,439)	$ (42,556)	$ 21,153	$ (107,373)
Other comprehensive income (loss):
Foreign currency translation adjustments	623	72	734	503
Available-for-sale investments:
Unrealized gain on investments, net of tax effect	(385)	(31)	712	(28)
Other comprehensive income, net of taxes	238	41	1,446	475
Comprehensive income (loss)	$ (49,201)	$ (42,515)	$ 22,599	$ (106,898)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Condensed Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]	Noncontrolling Interests [Member]
Balance at Dec. 31, 2017	$ 547,738	$ 825	$ 1,160,094	$ (1,795)	$ (630,657)	$ 19,271
Balance, Shares at Dec. 31, 2017		82,498,128
Impact of change in accounting principle upon adoption \| ASU 2016-01 [Member]	0	$ 0	0	(1,250)	1,250	0
Net income (loss)	(107,373)	0	0	0	(107,373)	0
Change in unrealized gain or loss on investments	(28)	0	0	(28)	0	0
Foreign currency translation adjustments	503	0	0	503	0	0
Shares issued from stock plans, net of payroll taxes paid	11,310	$ 23	11,287	0	0	0
Shares issued from stock plans, net of payroll taxes paid, Shares		2,348,614
Stock-based compensation	38,432	$ 0	38,432	0	0	0
Balance at Sep. 30, 2018	490,582	$ 848	1,209,813	(2,570)	(736,780)	19,271
Balance, Shares at Sep. 30, 2018		84,846,742
Balance at Jun. 30, 2018	514,802	$ 842	1,191,524	(2,611)	(694,224)	19,271
Balance, Shares at Jun. 30, 2018		84,182,844
Net income (loss)	(42,556)	$ 0	0	0	(42,556)	0
Change in unrealized gain or loss on investments	(31)	0	0	(31)	0	0
Foreign currency translation adjustments	72	0	0	72	0	0
Shares issued from stock plans, net of payroll taxes paid	3,972	$ 6	3,966	0	0	0
Shares issued from stock plans, net of payroll taxes paid, Shares		663,898
Stock-based compensation	14,323	$ 0	14,323	0	0	0
Balance at Sep. 30, 2018	490,582	$ 848	1,209,813	(2,570)	(736,780)	19,271
Balance, Shares at Sep. 30, 2018		84,846,742
Balance at Dec. 31, 2018	528,470	$ 854	1,226,453	(2,281)	(715,827)	19,271
Balance, Shares at Dec. 31, 2018		85,432,102
Impact of change in accounting principle upon adoption \| ASU 2016-02 [Member]	8,688	$ 0	0	0	8,688	0
Impact of change in accounting principle upon adoption \| ASU 2018-02 [Member]	0	0	0	611	(611)	0
Net income (loss)	21,153	0	0	0	21,153	0
Change in unrealized gain or loss on investments	712	0	0	712	0	0
Foreign currency translation adjustments	734	0	0	734	0	0
Shares issued from stock plans, net of payroll taxes paid	5,096	$ 18	5,078	0	0	0
Shares issued from stock plans, net of payroll taxes paid, Shares		1,778,567
Stock-based compensation	48,865	$ 0	48,865	0	0	0
Balance at Sep. 30, 2019	613,718	$ 872	1,280,396	(224)	(686,597)	19,271
Balance, Shares at Sep. 30, 2019		87,210,669
Balance at Jun. 30, 2019	648,302	$ 868	1,265,783	(462)	(637,158)	19,271
Balance, Shares at Jun. 30, 2019		86,847,072
Net income (loss)	(49,439)	$ 0	0	0	(49,439)	0
Change in unrealized gain or loss on investments	(385)	0	0	(385)	0	0
Foreign currency translation adjustments	623	0	0	623	0	0
Shares issued from stock plans, net of payroll taxes paid	(176)	$ 4	(180)	0	0	0
Shares issued from stock plans, net of payroll taxes paid, Shares		363,597
Stock-based compensation	14,793	$ 0	14,793	0	0	0
Balance at Sep. 30, 2019	$ 613,718	$ 872	$ 1,280,396	$ (224)	$ (686,597)	$ 19,271
Balance, Shares at Sep. 30, 2019		87,210,669

Condensed Consolidated Statement of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Operating activities
Net income (loss)	$ 21,153	$ (107,373)
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Depreciation	8,715	4,693
Amortization of finance lease right-of-use assets	7,720	0
Net amortization of premium and discount on investments	(3,354)	584
Unrealized loss (gain) on cash equivalents and short-term equity investments	(78)	1,103
Loss (gain) on disposal of property and equipment	(10)	53
Stock-based compensation	48,865	38,432
Realized foreign currency gain	0	(1,074)
Realized gain on sales of available-for-sale securities	0	(87)
Changes in operating assets and liabilities:
Accounts receivable	44,459	(14,735)
Inventories	(4,908)	0
Prepaid expenses and other current assets	(128,922)	1,935
Other assets	(953)	1,350
Accounts payable	(5,084)	4,622
Accrued and other liabilities	5,484	(9,885)
Deferred revenue	(50,915)	19,660
Lease obligations	0	35
Accrued interest for finance lease liabilities	104	0
Other long-term liabilities	24,069	2,008
Net cash used in operating activities	(33,655)	(58,679)
Investing activities
Purchases of property and equipment	(4,017)	(4,852)
Proceeds from sale of property and equipment	0	184
Purchases of available-for-sale securities and term deposit	(155,932)	(110,156)
Proceeds from sales of available-for-sale securities	0	8,167
Proceeds from maturities of investments	305,000	47,390
Net cash provided by (used in) investing activities	145,051	(59,267)
Financing activities
Borrowings under capital lease obligations	0	49
Repayments of finance lease liabilities	(8,810)	0
Repayments of lease obligations	(302)	(302)
Cash paid for payroll taxes on restricted stock unit releases	(10,614)	(13,288)
Proceeds from issuance of common stock	15,710	24,598
Net cash provided by (used in) financing activities	(4,016)	11,057
Effect of exchange rate change on cash and cash equivalents	(46)	(47)
Net increase (decrease) in cash and cash equivalents	107,334	(106,936)
Total cash and cash equivalents at beginning of period	89,258	673,658
Total cash and cash equivalents at end of period	$ 196,592	$ 566,722

Significant Accounting Policies

9 Months Ended

Sep. 30, 2019

Accounting Policies [Abstract]

Significant Accounting Policies

1.	Significant Accounting Policies

Description of Operations

FibroGen, Inc. (“FibroGen” or the “Company”) was incorporated in 1993 in Delaware and headquartered in San Francisco, California, with subsidiary offices in Beijing and Shanghai, People’s Republic of China (“China”). FibroGen is a leading biopharmaceutical company discovering and developing a pipeline of first-in-class therapeutics. The Company applies its pioneering expertise in hypoxia-inducible factor (“HIF”), connective tissue growth factor (“CTGF”) biology, and clinical development to advance innovative medicines for the treatment of anemia, fibrotic disease, and cancer. Roxadustat, the Company’s most advanced product, is an oral small molecule inhibitor of HIF prolyl hydroxylase (“HIF-PH”) activity, completing Phase 3 clinical development for the treatment of anemia in chronic kidney disease (“CKD”), with a New Drug Application (“NDA”) approved in China for dialysis and non-dialysis and in Japan for dialysis. The Company and its collaboration partners AstraZeneca AB (“AstraZeneca”) and Astellas Pharma Inc. (“Astellas”) are in the process of preparing an NDA for submission to the United States (“U.S.”) Food and Drug Administration (“FDA”) and a Marketing Authorization Application (“MAA”) for submission to the European Medicines Agency (“EMA”). Roxadustat is in Phase 3 clinical development in the U.S. and Europe and in Phase 2/3 development in China for anemia associated with myelodysplastic syndromes. Roxadustat is in Phase 2 clinical development for chemotherapy induced-anemia. Pamrevlumab, an anti-CTGF human monoclonal antibody, is in Phase 3 clinical development for the treatment of both idiopathic pulmonary fibrosis and pancreatic cancer. Pamrevlumab is also currently in a Phase 2 trial for Duchenne muscular dystrophy. FibroGen is also developing a biosynthetic cornea in China.

Basis of Presentation and Principles of Consolidation

The condensed consolidated financial statements include the accounts of FibroGen, its wholly owned subsidiaries and its majority-owned subsidiaries, FibroGen Europe Oy and FibroGen China Anemia Holdings, Ltd. (“FibroGen China”). All inter-company transactions and balances have been eliminated in consolidation. The Company operates in one segment — the discovery, development and commercialization of novel therapeutics to treat serious unmet medical needs.

The unaudited condensed consolidated financial statements and related disclosures have been prepared in accordance with accounting principles generally accepted in the U.S. (“U.S. GAAP”) applicable to interim financial reporting and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X of the U.S. Securities and Exchange Commission (“SEC”) and, therefore, do not include all information and footnote disclosures normally included in the annual consolidated financial statements. The financial information included herein should be read in conjunction with the consolidated financial statements and related notes in the Company’s Annual Report on Form 10-K filed with the SEC for the year ended December 31, 2018 (“2018 Form 10-K”).

The accounting policies used by the Company in its presentation of interim financial results are consistent with those presented in Note 2 to the consolidated financial statements included in the 2018 Form 10-K, except for the following:

Leases

The Company determines if an arrangement is a lease at inception date when it is given control of the underlying assets. The Company elected the practical expedient not to apply the lease recognition and measurement requirements to short-term leases, which is any lease with a term of 12 months or less as of the commencement date that does not include an option to purchase the underlying asset that the lessee is reasonably certain to exercise.

The Company’s building leases previously accounted for as build-to-suit arrangements prior to the adoption of Accounting Standards Codification (“ASC”) 842 - Leases (“ASC 842”) are accounted for as finance leases under the requirements of ASC 842.

Lease right-of-use (“ROU”) assets and lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at commencement date. As its leases do not typically provide an implicit rate, the Company uses its incremental borrowing rate based on the information available at commencement date in determining the present value of future payments. The Company will reassess the incremental borrowing rate periodically for application to any new leases or lease modifications or if any company-specific or general business conditions warrant.

Lease ROU assets include any lease payments made and initial direct costs incurred. The Company has lease agreements with lease and non-lease components. The Company generally accounts for each lease component separately from the non-lease components, and excludes all non-lease components from the calculation of minimum lease payments in measuring the ROU asset and lease liability.

The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease expense for minimum lease payments is recognized on a straight-line basis over the lease terms.

Regarding leases denominated in a foreign currency, the related ROU assets and the corresponding ROU asset amortization costs are remeasured using the exchange rate in effect at the date of initial recognition; the related lease liabilities are remeasured using the exchange rate in effect at the end of the reporting period; the lease costs and interest expenses related to lease liability accretion are remeasured using average exchange rates for the reporting period.

Finance leases are included in finance lease ROU assets, finance lease liabilities, current and non-current on the Company’s consolidated balance sheets. Operating leases are included in other assets, accrued and other current liabilities, and other long-term liabilities on the Company’s consolidated balance sheets.

Inventories

Inventories are stated at the lower of cost and net realizable value. The cost of inventories is determined using full absorption and standard costing, which approximates cost based on a first-in, first-out method. The Company reviews the standard costs of raw materials, work-in-process and finished goods periodically, and at least annually, to ensure that its inventories approximate current actual costs. The cost of inventories includes direct material costs, direct labor and manufacturing overhead. The Company regularly reviews the need to adjust the carrying value of excess and obsolete inventories to their estimated net realizable value, if less than cost, based primarily on its estimated forecast of product demand and product expiration period.

Net product sales

The Company sells roxadustat drug product through a number of pharmaceutical distributors in China. End customers order roxadustat drug product through the distributors and the Company ships drug product directly to these distributors. The delivery of roxadustat drug product to the distributors represents a single performance obligation for these transactions. Product revenue is recognized when control of the promised goods is transferred to the customer in an amount that reflects the consideration to which the Company expects to be entitled in exchange for those products, which is net of contractual sales discounts.

Use of Estimates

The preparation of the consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and reported amounts of revenues and expenses during the reporting period. The more significant areas requiring the use of management estimates and assumptions include valuation and recognition of revenue and deferred revenue, estimates of accruals related to clinical trial costs, valuation allowances for deferred tax assets, and valuation and recognition of stock-based compensation. On an ongoing basis, management reviews these estimates and assumptions. Changes in facts and circumstances may alter such estimates and actual results could differ from those estimates. In the Company’s opinion, the accompanying unaudited condensed consolidated financial statements include all normal recurring adjustments necessary for a fair statement of its financial position, results of operations and cash flows for the interim periods presented.

Net Income (Loss) per Share

The following is a reconciliation of the basic and diluted net income (loss) per share calculation for the periods presented (in thousands, except per share data):

	Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019		2018
Net income (loss)	$	(49,439	)	$	(42,556	)	$	21,153	$	(107,373	)
Weighted average shares used to compute net income (loss) per share:
Basic		87,007			84,508			86,390		83,713
Dilutive effect of potential common shares		—			—			5,605		—
Diluted		87,007			84,508			91,995		83,713

Net income (loss) per share:
Basic	$	(0.57	)	$	(0.50	)	$	0.24	$	(1.28	)
Diluted	$	(0.57	)	$	(0.50	)	$	0.23	$	(1.28	)

Diluted shares did not include 9.2 million and 3.6 million securities for the three and nine months ended September 30, 2019, and 9.3 million and 9.1 million securities for the three and nine months ended September 30, 2018, respectively, as they were anti-dilutive.

Recently Issued and Adopted Accounting Guidance

ASC 842

In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-02, Leases (Topic 842) (“ASU 2016-02”). Under this guidance, an entity is required to recognize ROU assets and lease liabilities on its balance sheet and disclose key information about leasing arrangements. This guidance offers specific accounting guidance for a lessee, a lessor and sale and leaseback transactions. Lessees and lessors are required to disclose qualitative and quantitative information about leasing arrangements to enable a user of the financial statements to assess the amount, timing and uncertainty of cash flows arising from leases. In July 2018, the FASB issued ASU 2018-11, Leases (Topic 842): Targeted Improvements (“ASU 2018-11”), which provides entities the option to initially apply ASU 2016-02 at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption.

The Company adopted the above guidance under ASC 842 as of January 1, 2019, using the modified retrospective transition method, through a cumulative-effect adjustment at the beginning of the first quarter of 2019. The Company elected the optional transition method under the guidance, which allowed it to continue applying previous lease guidance (ASC 840) for the comparative prior year periods presentation in the year of adoption. Accordingly, the Company recognized a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption.

In addition, the Company elected the package of transitional practical expedients permitted under the transition guidance under ASC 842, which among other things allows the Company to carry forward its historical lease classification, and not to reassess initial direct costs for any existing leases. Meanwhile, the Company did not elect the hindsight practical expedient because it has limited number of leases, lease terms are straightforward, and most of its lease renewals are undefined until negotiated.

In addition, the Company has elected the short-term accounting policy practical expedient and does not apply the balance sheet recognition requirements for short-term leases (excluding expenses relating to leases with a lease term of one month or less), by class of underlying asset to which the right of use relates. The Company has not elected the non-lease components practical expedient, and therefore accounts for each lease component separately from the non-lease components.

Upon adoption of ASC 842, the Company classified its existing building leases that were previously accounted for as build-to-suit arrangements as finance leases and applied the transition guidance. Accordingly, the Company derecognized the assets and liabilities previously recognized under ASC 840 build-to-suit guidance. In addition, as a result of applying the transition guidance, the Company also recorded an adjustment to the accumulated depreciation of related leasehold improvements to reflect a change in estimated useful life from the building life to the shorter of the building life and remaining lease term. Differences between the assets and liabilities derecognized were recorded to the opening balance of retained earnings.

The impacts to the select line items from the Company’s condensed consolidated balance sheet upon adoption of the ASC 842 guidance are as follows (in thousands):

Balance Sheet Line Item	Nature of Adjustment	New Lease Guidance Adoption Adjustment
Assets
Property and equipment, net	Derecognition - build-to-suit lease assets - building shell, cost	$	(53,880	)
	Derecognition - build-to-suit lease assets - building shell, accumulated depreciation		13,476
	Change of useful life - leasehold improvements, accumulated depreciation		(38,877	)
Finance lease right-of-use assets	Recognition - finance lease ROU assets		49,597
Other assets	Recognition - operating lease ROU assets		730
Liabilities
Accrued and other current liabilities	Derecognition - deferred rent, current		(619	)
	Derecognition - build-to-suit lease liabilities, current		(545	)
	Recognition - operating lease liabilities, current		404
Finance lease liabilities, current	Recognition - finance lease liabilities, current		11,499
Long-term portion of lease obligations	Derecognition - build-to-suit lease liabilities, non-current		(95,613	)
Deferred rent	Derecognition - deferred rent, non-current		(3,038	)
Finance lease liabilities, non-current	Recognition - finance lease liabilities, non-current		49,884
Other long-term liabilities	Recognition - operating lease liabilities, non-current		250
Stockholders’ equity
Accumulated deficit	Cumulative decrease to accumulated deficit	$	8,688

The adoption of this guidance did not have a material impact to the Company’s condensed consolidated statement of operations or condensed consolidated statement of cash flows for the nine months ended September 30, 2019.

ASU 2018-02

In February 2018, the FASB issued ASU 2018-02, Income Statement - Reporting Comprehensive Income: Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. This guidance allows for the reclassification from accumulated other comprehensive income to retained earnings for the stranded tax effects arising from the reduction of the U.S. federal statutory income tax rate from 35% to 21%. This guidance was effective for annual reporting period beginning after December 15, 2018, including interim periods. The Company adopted this guidance on January 1, 2019 using the modified retrospective approach. The impacts, based on the aggregate portfolio approach, to the Company’s accumulated other comprehensive loss and accumulated deficit upon adoption of this guidance are as follows (in thousands):

	Accumulated Other Comprehensive Loss			Accumulated Deficit
Balance at December 31, 2018	$	(2,281	)	$	(715,827	)
Impact of change in accounting principle upon adoption of ASU 2018-02		611			(611	)
Opening balance as of January 1, 2019	$	(1,670	)	$	(716,438	)

The adoption of this guidance had no impact to the Company’s condensed consolidated statement of operations or condensed consolidated statement of cash flows for the nine months ended September 30, 2019.

SEC Disclosure Requirement

In August 2018, the SEC adopted the final rule under SEC Release No. 33-10532, “Disclosure Update and Simplification,” amending certain disclosure requirements that were redundant, duplicative, overlapping, outdated or superseded. In addition, the amendments expanded the disclosure requirements on the analysis of stockholders’ equity for interim financial statements. Under the amendments, the changes in each caption of stockholders’ equity presented in the balance sheet must be provided in a note or separate statement. This analysis should present a reconciliation of the beginning balance to the ending balance of each period for which a statement of comprehensive income is presented. This final rule was effective as of November 5, 2018. Accordingly, the Company included the condensed consolidated statements of changes in stockholders’ equity in Form 10-Q starting the first quarter of 2019.

ASU 2018-07

In June 2018, the FASB issued ASU 2018-07, Compensation - Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting. This guidance expands the scope of Topic 718 to include share-based payment transactions for acquiring goods and services from nonemployees. The guidance also specifies that Topic 718 applies to all share-based payment transactions in which a grantor acquires goods or services to be used or consumed in a grantor’s own operations by issuing share-based payment awards. This guidance was effective for annual reporting period beginning after December 15, 2018, including interim periods. The Company adopted this guidance on January 1, 2019, and the adoption of this guidance had no impact to the Company’s consolidated financial statements.

Recently Issued Accounting Guidance Not Yet Adopted

In August 2018, the FASB issued ASU 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. This guidance requires capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). This guidance should be applied either retrospectively or prospectively and is effective for annual reporting period beginning after December 15, 2019 including interim periods, with early adoption permitted. The Company is currently evaluating the impact on its consolidated financial statements upon the adoption of this guidance.

In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement. This guidance amends existing fair value measurement disclosure requirements by adding, changing, or removing certain disclosures. This guidance is effective for annual reporting period beginning after December 15, 2019 including interim periods, with early adoption permitted. The amendments on changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements, and the narrative description of measurement uncertainty should be applied prospectively for only the most recent interim or annual period presented in the initial fiscal year of adoption. All other amendments should be applied retrospectively to all periods presented upon their effective date. The Company does not anticipate a material impact to its consolidated financial statements upon adoption of this guidance.

In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. Subsequently in April 2019, the FASB issued amendments to the guidance, ASU 2019-04, Codification Improvements to Topic 326, Financial Instruments—Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments, and in May 2019, ASU 2019-05, Financial Instruments – Credit Losses (Topic 326): Targeted Transition Relief. This guidance requires that financial assets measured at amortized cost be presented at the net amount expected to be collected. The measurement of expected credit losses is based on historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability. ASU 2019-04 clarifies that equity instruments without readily determinable fair values for which an entity has elected the measurement alternative should be remeasured to fair value as of the date that an observable transaction occurred. ASU 2019-05 provides an option to irrevocably elect to measure certain individual financial assets at fair value instead of amortized cost. The amendments should be applied on either a prospective transition or modified-retrospective approach depending on the subtopic. This guidance is effective for the annual reporting period beginning after December 15, 2019, including interim periods within that reporting period. The Company does not anticipate a material impact to its consolidated financial statements upon adoption of this guidance.

Collaboration Agreements

9 Months Ended

Sep. 30, 2019

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Collaboration Agreements

2.	Collaboration Agreements

Astellas Agreements

Japan Agreement

In June 2005, the Company entered into a collaboration agreement with Astellas for the development and commercialization (but not manufacture) of roxadustat for the treatment of anemia in Japan (“Japan Agreement”). Under this agreement, Astellas paid license fees and other consideration totaling $40.1 million (such amounts were fully received as of February 2009). Under the Japan Agreement, the Company is also eligible to receive from Astellas an aggregate of approximately $132.5 million in potential milestone payments, comprised of (i) up to $22.5 million in milestone payments upon achievement of specified clinical and development milestone events (such amounts were fully received as of July 2016), (ii) up to $95.0 million in milestone payments upon achievement of specified regulatory milestone events, and (iii) up to approximately $15.0 million in milestone payments upon the achievement of specified commercial sales milestone. The aggregate amount of such consideration received through September 30, 2019 totals $77.6 million.

In September 2019, Japan’s Ministry of Health, Labour and Welfare approved Evrenzo® (generic name: roxadustat; tradename Evrenzo® in Japan) for the treatment of anemia associated with CKD in dialysis patients. This approval triggered a $12.5 million milestone payable to the Company by Astellas under the Japan Agreement. Accordingly, the consideration of $12.5 million associated with this milestone was included in the transaction price and allocated to performance obligations under the Japan Agreement in the third quarter of 2019, substantially all of which was recognized as revenue during the period from performance obligations satisfied or partially satisfied as of September 30, 2019.

Europe Agreement

In April 2006, the Company entered into a separate collaboration agreement with Astellas for the development and commercialization of roxadustat for the treatment of anemia in Europe, the Middle East, the Commonwealth of Independent States and South Africa (“Europe Agreement”). Under the terms of the Europe Agreement, Astellas paid license fees and other upfront consideration totaling $320.0 million (such amounts were fully received as of February 2009). Under the Europe Agreement, the Company is also eligible to receive from Astellas an aggregate of approximately $425.0 million in potential milestone payments, comprised of (i) up to $90.0 million in milestone payments upon achievement of specified clinical and development milestone events (such amounts were fully received as of 2012), (ii) up to $335.0 million in milestone payments upon achievement of specified regulatory milestone events. Under the Europe Agreement, Astellas committed to fund 50% of joint development costs for Europe and North America, and all territory-specific costs. The Europe Agreement also provides for tiered payments based on net sales of product (as defined) in the low 20% range. The aggregate amount of such consideration received through September 30, 2019 totals $410.0 million.

In the fourth quarter of 2018, the Company was engaged in the final stages of review with its partners over the proposed development of roxadustat for the treatment of chemotherapy induced anemia (“CIA”). AstraZeneca and Astellas approved the program in December 2018 and January 2019, respectively. Costs associated with the development of this indication are expected to be shared 50/50 between AstraZeneca and Astellas. For revenue recognition purposes, the Company concluded that this new indication represents a modification to the Europe agreements and will be accounted for separately, meaning the development costs associated with the new indications are distinct from the original development costs. The development service period for roxadustat for the treatment of CIA under the Europe Agreement is estimated to continue through the end of 2023 to allow for development of this indication.

During the second quarter of 2019, the Company received positive topline results from analyses of pooled major adverse cardiac event (“MACE”) and MACE+ data from its Phase 3 trials evaluating roxadustat as a treatment for dialysis and non-dialysis CKD patients, enabling Astellas to prepare for an MAA submission to the EMA during their fiscal year 2019, which ends on March 31, 2020, following the Company’s NDA submission to the FDA. The Company evaluated the two regulatory milestone payments associated with the planned MAA submission and concluded that these milestones became probable of being achieved in the second quarter of 2019. Accordingly, the total consideration of $130.0 million associated with these milestones was included in the transaction price and allocated to performance obligations under the Europe Agreement in the second quarter of 2019, of which $129.0 million was recognized as revenue during the period from performance obligations satisfied or partially satisfied as of September 30, 2019. According to the Europe Agreement, these milestone payments are not billable to Astellas until the submission of an MAA, therefore this $130.0 million remained as an unbilled contract asset as of September 30, 2019.

AstraZeneca Agreements

U.S./Rest of World (“RoW”) Agreement

Effective July 30, 2013, the Company entered into a collaboration agreement with AstraZeneca for the development and commercialization of roxadustat for the treatment of anemia in the U.S. and all other countries in the world, other than China, not previously licensed under the Astellas Europe and Astellas Japan Agreements (“U.S./RoW Agreement”). It also excludes China, which is covered by a separate agreement with AstraZeneca described below. Under the terms of the U.S./RoW Agreement, AstraZeneca paid upfront, non-contingent, non-refundable and time-based payments totaling $374.0 million (such amounts were fully received as of June 2016). Under the U.S./RoW Agreement, the Company is also eligible to receive from AstraZeneca an aggregate of approximately $875.0 million in potential milestone payments, comprised of (i) up to $65.0 million in milestone payments upon achievement of specified clinical and development milestone events, $15.0 million of which was received in 2015 as a result of the finalization of its two audited pre-clinical carcinogenicity study reports, (ii) up to $325.0 million in milestone payments upon achievement of specified regulatory milestone events, (iii) up to $160.0 million in milestone payments related to activity by potential competitors and (iv) up to approximately $325.0 million in milestone payments upon the achievement of specified commercial sales events. The aggregate amount of such consideration received through September 30, 2019 totals $389.0 million.

As mentioned above, during the second quarter of 2019, the Company received positive topline results from analyses of pooled MACE and MACE+ data from its Phase 3 trials for roxadustat, enabling the Company’s NDA submission to the FDA. The Company evaluated the regulatory milestone payment associated with this planned NDA submission and concluded that this milestone became probable of being achieved in the second quarter of 2019. Accordingly, the consideration of $50.0 million associated with this milestone was included in the transaction price and allocated to performance obligations under the U.S./ RoW Agreement in the second quarter of 2019, of which $42.1 million was recognized as revenue during the period from performance obligations satisfied or partially satisfied as of September 30, 2019. According to the U.S/RoW Agreement, this milestone payment is not billable to AstraZeneca until the Company has submitted the NDA, therefore this $50.0 million remained as an unbilled contract asset as of September 30, 2019.

China Agreement

Effective July 30, 2013, the Company (through its subsidiaries affiliated with China) entered into a collaboration agreement with AstraZeneca for the development and commercialization (but not manufacture) of roxadustat for the treatment of anemia in China (“China Agreement”). Under the terms of the China Agreement, AstraZeneca paid upfront, non-contingent and non-refundable payments totaling $28.2 million (such amounts were fully received in 2014). Under the China Agreement, the Company is also eligible to receive from AstraZeneca an aggregate of approximately $348.5 million in potential milestone payments, comprised of (i) up to $15.0 million in milestone payments upon achievement of specified clinical and development milestone events, (ii) up to $146.0 million in milestone payments upon achievement of specified regulatory milestone events, and (iii) up to approximately $187.5 million in milestone payments upon the achievement of specified commercial sales and other events. The China Agreement is structured as a 50/50 profit or loss share (as defined) and provides for joint development costs (including capital and equipment costs for construction of the manufacturing plant in China), to be shared equally during the development. The aggregate amount of such consideration received through September 30, 2019 totals $55.2 million.

As mentioned above, in the fourth quarter of 2018, the Company was engaged in the final stages of review with its partners over the proposed development of roxadustat for the treatment of CIA. AstraZeneca and Astellas approved the program in December 2018 and January 2019, respectively. Costs associated with the development of this indication are expected to be shared 50/50 between AstraZeneca and Astellas. In addition to CIA, in December 2018, anemia of chronic inflammation (“ACI”) and multiple myeloma (“MM”) have been approved for development by AstraZeneca and is expected to be fully funded by them. For revenue recognition purposes, the Company concluded that the addition of these new indications represents a modification to the collaboration agreements and will be accounted for separately, meaning the development costs associated with the new indications are distinct from the original development costs. The development service period for roxadustat for the treatment of CIA, ACI and MM under the AstraZeneca agreements is estimated to continue through the end of 2024, to allow for development of these additional indications.

On December 17, 2018, FibroGen (China) Medical Technology Development Co., Ltd. (“FibroGen Beijing”), received marketing authorization from the National Medical Products Administration (“NMPA”) for roxadustat, a first-in-class HIF-PH inhibitor, for the treatment of anemia caused by CKD in patients on dialysis. This approval triggered a $6.0 million milestone payable to the Company by AstraZeneca. On December 29, 2018, FibroGen Beijing received First Manufacturing Approval for a Product in the Field in the Territory, which allows production for Phase IV clinical studies, patients’ early experience programs, donation programs, as well as to supply products for testing and assessments required prior to launch. This approval triggered a $6.0 million milestone payable to the Company by AstraZeneca. These milestones payments were received in the first quarter of 2019.

Summary of Revenue Recognized Under the Collaboration Agreements

The table below summarizes the accounting treatment for the various performance obligations pursuant to each of the Astellas and AstraZeneca agreements. License amounts identified below are included in the “License revenue” line item in the condensed consolidated statements of operations. All other elements identified below are included in the “Development and other revenue” line item in the condensed consolidated statements of operations.

Amounts recognized as revenue under the Japan Agreement were as follows (in thousands):

		Three Months Ended September 30,				Nine Months Ended September 30,
Agreement	Performance Obligation	2019		2018		2019		2018
Japan	License revenue	$	11,935	$	—	$	11,935	$	14,323
	Development revenue	$	537	$	474	$	1,151	$	2,065

The transaction price related to consideration received and accounts receivable has been allocated to each of the following performance obligations under the Japan Agreement, along with any associated deferred revenue as follows (in thousands):

Japan Agreement	Cumulative Revenue Through September 30, 2019		Deferred Revenue at September 30, 2019		Total Consideration Through September 30, 2019
License	$	86,024	$	—	$	86,024
Development revenue		15,060		312		15,372
Total license and development revenue	$	101,084	$	312	$	101,396

The revenue recognized under the Japan Agreement for the three months ended September 30, 2019 included an increase in revenue of $12.3 million resulting from changes to estimated variable consideration in the current period relating to performance obligations satisfied or partially satisfied in previous periods. The remainder of the transaction price related to the Japan Agreement includes $0.2 million of variable consideration from estimated future co-development billing and is expected to be recognized over the remaining development service period.

Amounts recognized as revenue under the Europe Agreement were as follows (in thousands):

		Three Months Ended September 30,				Nine Months Ended September 30,
Agreement	Performance Obligation	2019		2018		2019		2018
Europe	License revenue	$	—	$	—	$	117,470	$	—
	Development revenue	$	2,996	$	4,658	$	24,463	$	14,384

The transaction price related to consideration received and accounts receivable has been allocated to each of the following performance obligations under the Europe Agreement, along with any associated deferred revenue as follows (in thousands):

Europe Agreement	Cumulative Revenue Through September 30, 2019		Deferred Revenue at September 30, 2019			Total Consideration Through September 30, 2019
License	$	487,951	$	—		$	487,951
Development revenue		227,300		3,988			231,288
Total license and development revenue	$	715,251	$	3,988	*	$	719,239

_______________________________________________________________________________________________________

Contract assets and liabilities related to rights and obligations in the same contract are recorded net on the condensed consolidated balance sheets. As of September 30, 2019, prepaid expenses and other current assets included a net unbilled contract asset of $126.0 million related to the Europe Agreement, which represents the net of the above-mentioned unbilled contract asset of $130.0 million, and $4.0 million of deferred revenue presented above.

The revenue recognized under the Europe Agreement for the three months ended September 30, 2019 included a decrease in revenue of $2.9 million resulting from changes to estimated variable consideration in the current period relating to performance obligations satisfied or partially satisfied in previous periods. The remainder of the transaction price related to the Europe Agreement includes $42.4 million of variable consideration from estimated future co-development billing and is expected to be recognized over the remaining development service period.

Amounts recognized as revenue under the U.S./RoW Agreement were as follows (in thousands):

		Three Months Ended September 30,				Nine Months Ended September 30,
Agreement	Performance Obligation	2019		2018		2019		2018
U.S. / RoW and China	License revenue	$	—	$	—	$	33,112	$	—
	Development revenue		17,106		23,895		59,872		74,096
	China performance obligation	$	19	$	—	$	19	$	—

The transaction price related to consideration received and accounts receivable has been allocated to each of the following performance obligations under the U.S./RoW Agreement and China Agreement, along with any associated deferred revenue as follows (in thousands):

U.S. / RoW and China Agreements	Cumulative Revenue Through September 30, 2019		Deferred Revenue at September 30, 2019			Total Consideration Through September 30, 2019
License	$	327,275	$	—		$	327,275
Co-development, information sharing & committee services		468,509		11,317			479,826
China performance obligation		19		137,330			137,349
Total license and development revenue	$	795,803	$	148,647	*	$	944,450

_______________________________________________________________________________________________________

Contract assets and liabilities related to rights and obligations in the same contract are recorded net on the condensed consolidated balance sheets. As of September 30, 2019, long-term deferred revenue included $98.6 million related to the U.S./RoW and China Agreement, which represents the net of $148.6 million of deferred revenue presented above and the above-mentioned $50.0 million unbilled contract asset.

The revenue recognized under the U.S./RoW Agreement for the three months ended September 30, 2019 included an increase in revenue of $3.5 million resulting from changes to estimated variable consideration in the current period relating to performance obligations satisfied or partially satisfied in previous periods. The remainder of the transaction price related to the U.S./RoW Agreement and China Agreement includes $186.6 million of variable consideration from estimated future co-development billing and is expected to be recognized over the remaining development service period, except for amounts allocated to the China performance obligation, which are expected to be recognized in a pattern consistent with estimated deliveries of the commercial drug product.

Product Revenue

During the third quarter of 2019, the Company started commercial sales of roxadustat drug product in China, and recognized related product revenue of $0.6 million in the same period, which was net of immaterial contractual sales discounts.

Other Revenues

Other revenues consist primarily of collagen material sold for research purposes. Other revenues were immaterial for all periods presented.

Deferred Revenue

Deferred revenue represents amounts billed, or in certain cases, yet to be billed to the Company’s collaboration partners for which the related revenues have not been recognized because one or more of the revenue recognition criteria have not been met. The current portion of deferred revenue represents the amount to be recognized within one year from the balance sheet date based on the estimated performance period of the underlying performance obligations. The long term portion of deferred revenue represents amounts to be recognized after one year through the end of the non-contingent performance period of the underlying performance obligations.

Deferred revenue includes amounts allocated to the China unit of accounting under the AstraZeneca arrangement as revenue recognition associated with this unit of accounting is tied to the commercial launch of the products within China. As of December 31, 2018, such deferred revenue was included in long-term deferred revenue. As of September 30, 2019, following receipt of the Chinese Good Manufacturing Practices license by FibroGen Beijing in the second quarter of 2019, approximately $0.7 million of the related deferred revenue was included in short-term deferred revenue, which represents the amount of deferred revenue associated with the China unit of accounting that is expected to be recognized as a result of the transfer of control of commercial drug product in China.

Fair Value Measurements

9 Months Ended

Sep. 30, 2019

Fair Value Disclosures [Abstract]

Fair Value Measurements

3.	Fair Value Measurements

The fair values of the Company’s financial assets that are measured on a recurring basis are as follows (in thousands):

	September 30, 2019
	Level 1		Level 2		Level 3		Total
US treasury notes and bills	$	226,590	$	175,450	$	—	$	402,040
Bond and mutual funds		10,748		—		—		10,748
Equity investments		251		—		—		251
Money market funds		105,822		—		—		105,822
Certificate of deposit		—		30,000		—		30,000
Total	$	343,411	$	205,450	$	—	$	548,861

	December 31, 2018
	Level 1		Level 2		Level 3		Total
US treasury notes and bills	$	292,317	$	224,953	$	—	$	517,270
Bond and mutual funds		10,484		—		—		10,484
Equity investments		234		—		—		234
Money market funds		541		—		—		541
Term deposit		—		80,000		—		80,000
Certificate of deposit		—		29,910		—		29,910
Total	$	303,576	$	334,863	$	—	$	638,439

Our Level 2 investments are valued using third-party pricing sources. The pricing services utilize industry standard valuation models, including both income and market-based approaches, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include reported trades of and broker/dealer quotes on the same or similar investments, issuer credit spreads, benchmark investments, prepayment/default projections based on historical data and other observable inputs.

The fair values of the Company’s financial liabilities that are carried at historical cost are as follows (in thousands):

	September 30, 2019
	Level 1		Level 2		Level 3		Total
Lease obligations	$	—	$	—	$	1,645	$	1,645

	December 31, 2018
	Level 1		Level 2		Level 3		Total
Lease obligations	$	—	$	—	$	98,105	$	98,105

The fair values of the Company’s financial liabilities were derived by using an income approach, which required Level 3 inputs such as discounted estimated future cash flows.

As of December 31, 2018, the Company had $96.2 million in lease obligations related to its building leases under build-to-suit arrangements. Upon the adoption of ASC 842 as of January 1, 2019, using the modified retrospective transition method, the Company derecognized these liabilities previously recognized under ASC 840 build-to-suit designation. Refer to Note 1 for details.

The remaining balance of $1.6 million as of September 30, 2019 under lease obligations is related to an expansion option in the Company’s long-term property lease with Shorenstein Properties LLC (“Alexandria” or “landlord”). This expansion option allowed the Company to occupy part of an adjacent building within 31 months of the lease commencement date in 2008. In 2012, the Company gave notice to its landlord that it would not exercise this expansion option, which resulted in a $5.0 million payment liability to the landlord that is financed over the remaining lease term to 2023.

There were no transfers of assets or liabilities between levels for any of the periods presented.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Leases

9 Months Ended

Sep. 30, 2019

Leases [Abstract]

Leases

The Company currently has two building leases treated as finance leases.

In 2006, the Company entered into a long-term property lease with Alexandria for its corporate headquarters in San Francisco, California, with an initial term of 15 years, scheduled to expire in 2023. The Company has an option to extend the lease for an additional 10 years through 2033. The lease contract provides for a fixed annual rent, with scheduled increases of two percent that occur on each anniversary of the rent commencement date. This lease requires the Company to pay all costs of ownership, operation, and maintenance of the premises, including without limitation all operating costs, insurance costs, and taxes.

In 2013, the Company entered into a long-term property lease with Beijing Economic-Technological Development Area (“BDA”) Management Committee for a pilot plant located in Beijing Yizhuang Biomedical Park (“BYBP”) of BDA. The building is leased for an initial lease term of eight years, scheduled to expire in 2021. Renewal options are not specified within the lease contract. The lease contract provides for fixed quarterly rent payments, with scheduled increases that occur as detailed in the lease contract. This lease requires the Company to pay all operating and maintenance costs, and a fixed amount for property management fees.

The Company currently has six additional real estate leases for space within a building, which are treated as operating leases. These leases have lease terms ranging from two to four years. These lease contracts provide for fixed quarterly rent payments, and require the Company to pay operating and maintenance costs, and a fixed amount for property management fees.

In addition, the Company has several immaterial lease arrangements for office equipment, scientific devices and automobile leases, with contracted lease terms ranging from two to five years, treated as finance leases or operating leases, respectively.

The Company’s lease assets and related lease liabilities were as follows (in thousands):

	Balance Sheet Line Item	September 30, 2019
Assets
Finance:
Right-of-use assets - cost		$	49,784
Accumulated amortization			(7,720	)
Finance lease right-of-use assets, net	Finance lease right-of-use assets		42,064
Operating:
Right-of-use assets - cost			2,723
Accumulated amortization			(531	)
Operating lease right-of-use assets, net	Other assets		2,192
Total lease assets		$	44,256

Liabilities
Current:
Finance lease liabilities	Finance lease liabilities, current	$	12,149
Operating lease liabilities	Accrued and other current liabilities		998
Non-current:
Finance lease liabilities	Finance lease liabilities, non-current		40,713
Operating lease liabilities	Other long-term liabilities		1,133
Total lease liabilities		$	54,993

The components of lease expense were as follows (in thousands):

	Statement of Operations Line Item	Three Months Ended September 30, 2019			Nine Months Ended September 30, 2019
Finance lease cost:
Amortization of right-of-use assets	Selling, general and administrative expenses	$	2,580		$	7,720
Interest on lease liabilities	Interest expense		578			1,826
Operating lease cost	Research and development, Selling, general and administrative expenses		290			579
Sublease income	Selling, general and administrative expenses		(310	)		(1,135	)
Total lease cost		$	3,138		$	8,990

Supplemental cash flow information related to leases were as follows (in thousands):

	Nine Months Ended September 30, 2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$	540
Operating cash flows from finance leases		1,640
Financing cash flows from finance leases		8,810
Right-of-use assets obtained in exchange for new lease liabilities:
Finance leases		49,784
Operating leases	$	2,723

Lease term and discount rate were as follows at September 30, 2019:

	September 30, 2019
Weighted-average remaining lease term (years):
Finance leases		3.8
Operating leases		2.3
Weighted-average discount rate:
Finance leases		4.43	%
Operating leases		4.75	%

Maturities of lease liabilities are as follows:

Year Ending	Finance Leases			Operating Leases
2019 (Remaining three month period)	$	3,466		$	280
2020		14,060			1,013
2021		13,675			651
2022		13,878			300
2023		12,523			—
Total future lease payments		57,602			2,244
Less: Interest		(4,740	)		(113	)
Present value of lease liabilities	$	52,862		$	2,131

The following information was previously disclosed under ASC 840 as of December 31, 2018:

Future minimum lease payments under all non-cancelable operating lease obligations as of December 31, 2018 were as follows (in thousands):

Year Ending	Operating Leases
2019	$	444
2020		232
2021		25
2022		16
2023		—
Total minimum payments	$	717

Future minimum lease payments, on a consolidated basis, under the Company’s facility lease financing obligations as of December 31, 2018 were as follows (in thousands):

Year Ending	Lease financing obligations
2019	$	14,379
2020		14,664
2021		14,179
2022		14,335
2023		12,872
Total minimum payments	$	70,429

Balance Sheet Components

9 Months Ended

Sep. 30, 2019

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Balance Sheet Components

5.	Balance Sheet Components

Cash and Cash Equivalents

Cash and cash equivalents consisted of the following (in thousands):

	September 30, 2019		December 31, 2018
Cash	$	90,770	$	38,783
US treasury notes and bills		—		49,934
Money market funds		105,822		541
Total cash and cash equivalents	$	196,592	$	89,258

At September 30, 2019 and December 31, 2018, a total of $18.1 million and $21.9 million, respectively, of the Company’s cash and cash equivalents were held outside of the U.S. in its foreign subsidiaries to be used primarily for its China operations.

Investments

The Company’s investments consist of available-for-sale debt investments, marketable equity investments, a term deposit and a certificate of deposit. The amortized cost, gross unrealized holding gains or losses, and fair value of the Company’s available-for-sale investments by major investments type are summarized in the tables below (in thousands):

	September 30, 2019
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Fair Value
US treasury notes and bills	$	401,377	$	688	$	(25	)	$	402,040
Certificates of deposit		30,000		—		—			30,000
Bond and mutual funds		10,668		80		—			10,748
Equity investments		125		126		—			251
Total investments	$	442,170	$	894	$	(25	)	$	443,039

	December 31, 2018
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Fair Value
US treasury notes and bills	$	467,296	$	109	$	(69	)	$	467,336
Term deposit		80,000		—		—			80,000
Certificates of deposit		30,000		—		(90	)		29,910
Bond and mutual funds		10,464		20		—			10,484
Equity investments		125		109		—			234
Total investments	$	587,885	$	238	$	(159	)	$	587,964

At September 30, 2019, all of the available-for-sale investments had contractual maturities within one year. The Company periodically reviews its available-for-sale investments and term deposit for other-than-temporary impairment. The Company considers factors such as the duration, severity and the reason for the decline in value, the potential recovery period and its intent to sell. For debt securities, the Company also considers whether (i) it is more likely than not that the Company will be required to sell the debt securities before recovery of their amortized cost basis, and (ii) the amortized cost basis cannot be recovered as a result of credit losses. During the three and nine months ended September 30, 2019 and 2018, the Company did not recognize any other-than-temporary impairment loss.

Inventories

Inventories consisted of the following (in thousands):

	September 30, 2019
Raw materials	$	658
Work-in-progress		1,155
Finished goods		3,095
Total inventories	$	4,908

The Company started capitalizing inventory costs in June 2019 when FibroGen China began productions of roxadustat for commercial sales purposes. There was no provision to write-down excess and obsolete inventory for the three and nine months ended September 30, 2019.

Prepaid expenses and other current assets

Prepaid expenses and other current assets consisted of the following (in thousands):

	September 30, 2019			December 31, 2018
Unbilled contract assets	$	180,000		$	—
Deferred revenues from associated contracts		(53,988	)		—
Net unbilled contract assets		126,012			—
Prepaid assets		4,051			2,705
Other current assets		3,652			2,224
Total prepaid expenses and other current assets	$	133,715		$	4,929

The unbilled contract assets as of September 30, 2019 were related to two regulatory milestones totaling $130.0 million under the Europe Agreement with Astellas associated with the planned MAA submission in Europe, and a $50.0 million regulatory milestone under the U.S./RoW Agreement with AstraZeneca associated with the planned NDA submission in the U.S. See Note 2 for details.

Property and Equipment

Property and equipment consisted of the following (in thousands):

	September 30, 2019			December 31, 2018
Leasehold improvements	$	101,339		$	101,200
Building shell		—			53,880
Laboratory equipment		16,932			16,405
Machinery		8,691			8,382
Computer equipment		7,227			6,473
Furniture and fixtures		5,789			5,690
Construction in progress		2,332			367
Total property and equipment	$	142,310		$	192,397
Less: accumulated depreciation		(99,102	)		(65,199	)
Property and equipment, net	$	43,208		$	127,198

As of December 31, 2018, the Company had $53.9 million building shell cost and $13.5 million accumulated depreciation related to its building leases under build-to-suit arrangements. Upon the adoption of ASC 842 as of January 1, 2019, using the modified retrospective transition method, the Company derecognized these assets previously recognized under ASC 840 build-to-suit designation. Up to December 31, 2018, the leasehold improvements related to these building leases were depreciated over the life of the building under ASC 840. Upon the adoption of ASC 842, these leasehold improvements should have a useful life based on the lease term. As a result, at the adoption date, the Company recorded a cumulative adjustment of $38.9 million to the accumulated depreciation for these leasehold improvements so that their net balance equals the undepreciated amount had the useful life of the leasehold improvements always been equal to the lease terms. Refer to Note 1 for details.

Accrued Liabilities

Accrued liabilities consisted of the following (in thousands):

	September 30, 2019		December 31, 2018
Preclinical and clinical trial accruals	$	41,546	$	35,413
Payroll and related accruals		17,604		21,430
Property taxes and other		2,389		1,095
Professional services		4,063		2,648
Other		5,223		5,537
Total accrued liabilities	$	70,825	$	66,123

Stock-Based Compensation

9 Months Ended

Sep. 30, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

6.	Stock-Based Compensation

Stock-based compensation expense was allocated to research and development and selling, general and administrative expense as follows (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
Research and development	$	10,185	$	8,465	$	30,214	$	22,729
Selling, general and administrative		4,608		5,858		18,651		15,703
Total stock-based compensation expense	$	14,793	$	14,323	$	48,865	$	38,432

The assumptions used to estimate the fair value of stock options granted and purchases under the Company’s 2014 Employee Share Purchase Plan (“ESPP”) using the Black-Scholes option valuation model were as follows:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019			2018
Stock Options
Expected term (in years)		5.3			5.3			5.3			5.4
Expected volatility		67.8	%		68.1	%		67.9	%		67.8	%
Risk-free interest rate		1.7	%		2.9	%		2.4	%		2.7	%
Expected dividend yield		—			—			—			—
Weighted average estimated fair value	$	25.17		$	35.99		$	32.44		$	32.37

ESPPs
Expected term (in years)	0.5 - 2.0			0.5 - 2.0			0.5 - 2.0			0.5 - 2.0
Expected volatility	48.1 - 62.1		%	47.3 - 72.8		%	48.1 - 62.1		%	47.3 - 75.3		%
Risk-free interest rate	1.6 - 2.9		%	1.0 - 2.6		%	1.3 - 2.9		%	0.8 - 2.6		%
Expected dividend yield		—			—			—			—
Weighted average estimated fair value	$	19.27		$	20.10		$	19.53		$	15.27

Income Taxes

9 Months Ended

Sep. 30, 2019

Income Tax Disclosure [Abstract]

Income Taxes

7.	Income Taxes

The provisions for income taxes for the three and nine months ended September 30, 2019 and 2018 were due to foreign taxes.

Based upon the weight of available evidence, which includes its historical operating performance, reported cumulative net losses since inception, the Company has established and continues to maintain a full valuation allowance against its deferred tax assets as it does not currently believe that realization of those assets is more likely than not.

Related Party Transactions

9 Months Ended

Sep. 30, 2019

Related Party Transactions

8.	Related Party Transactions

Astellas is an equity investor in the Company and considered a related party. The Company recorded revenue related to collaboration agreements with Astellas of $15.5 million and $5.1 million for the three months ended September 30, 2019 and 2018, respectively, and $155.0 million and $30.8 million for the nine months ended September 30, 2019 and 2018, respectively.

The Company recorded expense related to collaboration agreements with Astellas of $0.9 million and $0.4 million during the three months ended September 30, 2019 and 2018, respectively, and $2.2 million and $1.1 million during the nine months ended September 30, 2019 and 2018.

As of September 30, 2019 and December 31, 2018, accounts receivable from Astellas were $17.7 million and $47.2 million, respectively, and amounts due to Astellas were $1.7 million and $0.4 million, respectively. The accounts receivable from Astellas as of September 30, 2019 included $12.5 million of the milestone payment the Japan Agreement related to Japan’s NDA approval by the Ministry of Health, Labour and Welfare for the treatment of anemia associated with CKD in dialysis patients. The accounts receivable from Astellas as of December 31, 2018 included $43.8 million related to the delivery of roxadustat active pharmaceutical ingredients to Astellas during the fourth quarter of 2018, pursuant to an amendment to the Japan Agreement that will allow Astellas to manufacture roxadustat drug product for commercialization in Japan. This amount was received during the first quarter of 2019.

Prepaid expenses and other current assets as of September 30, 2019 included $126.0 million of net unbilled contract asset, representing a $130.0 million unbilled contract asset related to two regulatory milestones under the Europe Agreement with Astellas associated with the planned MAA submission to the EMA, net of $4.0 million of associated deferred revenue. See Note 2 for details. According to the Europe Agreement, this $130.0 million is not billable to Astellas until the submission of an MAA, therefore the net contract asset was included in the prepaid expenses and other current assets line on the Company’s condensed consolidated balance sheet as of September 30, 2019. There was no such contract asset balance as of December 31, 2018.

Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2019

Accounting Policies [Abstract]

Description of Operations

Basis of Presentation and Principles of Consolidation

Net product sales

Net Income (Loss) per Share

The following is a reconciliation of the basic and diluted net income (loss) per share calculation for the periods presented (in thousands, except per share data):

	Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019		2018
Net income (loss)	$	(49,439	)	$	(42,556	)	$	21,153	$	(107,373	)
Weighted average shares used to compute net income (loss) per share:
Basic		87,007			84,508			86,390		83,713
Dilutive effect of potential common shares		—			—			5,605		—
Diluted		87,007			84,508			91,995		83,713

Net income (loss) per share:
Basic	$	(0.57	)	$	(0.50	)	$	0.24	$	(1.28	)
Diluted	$	(0.57	)	$	(0.50	)	$	0.23	$	(1.28	)

Recently Issued and Adopted Accounting Guidance

ASC 842

The impacts to the select line items from the Company’s condensed consolidated balance sheet upon adoption of the ASC 842 guidance are as follows (in thousands):

Balance Sheet Line Item	Nature of Adjustment	New Lease Guidance Adoption Adjustment
Assets
Property and equipment, net	Derecognition - build-to-suit lease assets - building shell, cost	$	(53,880	)
	Derecognition - build-to-suit lease assets - building shell, accumulated depreciation		13,476
	Change of useful life - leasehold improvements, accumulated depreciation		(38,877	)
Finance lease right-of-use assets	Recognition - finance lease ROU assets		49,597
Other assets	Recognition - operating lease ROU assets		730
Liabilities
Accrued and other current liabilities	Derecognition - deferred rent, current		(619	)
	Derecognition - build-to-suit lease liabilities, current		(545	)
	Recognition - operating lease liabilities, current		404
Finance lease liabilities, current	Recognition - finance lease liabilities, current		11,499
Long-term portion of lease obligations	Derecognition - build-to-suit lease liabilities, non-current		(95,613	)
Deferred rent	Derecognition - deferred rent, non-current		(3,038	)
Finance lease liabilities, non-current	Recognition - finance lease liabilities, non-current		49,884
Other long-term liabilities	Recognition - operating lease liabilities, non-current		250
Stockholders’ equity
Accumulated deficit	Cumulative decrease to accumulated deficit	$	8,688

ASU 2018-02

	Accumulated Other Comprehensive Loss			Accumulated Deficit
Balance at December 31, 2018	$	(2,281	)	$	(715,827	)
Impact of change in accounting principle upon adoption of ASU 2018-02		611			(611	)
Opening balance as of January 1, 2019	$	(1,670	)	$	(716,438	)

SEC Disclosure Requirement

ASU 2018-07

Recently Issued Accounting Guidance Not Yet Adopted

Collaboration Arrangements

Astellas Agreements

Japan Agreement

Europe Agreement

AstraZeneca Agreements

U.S./Rest of World (“RoW”) Agreement

China Agreement

Other Revenues

Product Revenue

Other Revenues

Other revenues consist primarily of collagen material sold for research purposes. Other revenues were immaterial for all periods presented.

Product Revenue

Deferred Revenue

Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2019

Summary of Reconciliation of Basic and Diluted Net Income (Loss) Per Share Calculation

The following is a reconciliation of the basic and diluted net income (loss) per share calculation for the periods presented (in thousands, except per share data):

	Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019		2018
Net income (loss)	$	(49,439	)	$	(42,556	)	$	21,153	$	(107,373	)
Weighted average shares used to compute net income (loss) per share:
Basic		87,007			84,508			86,390		83,713
Dilutive effect of potential common shares		—			—			5,605		—
Diluted		87,007			84,508			91,995		83,713

Net income (loss) per share:
Basic	$	(0.57	)	$	(0.50	)	$	0.24	$	(1.28	)
Diluted	$	(0.57	)	$	(0.50	)	$	0.23	$	(1.28	)

ASU 2016-02 [Member]

Schedule of Impacts Upon Adoption of New Guidance

The impacts to the select line items from the Company’s condensed consolidated balance sheet upon adoption of the ASC 842 guidance are as follows (in thousands):

Balance Sheet Line Item	Nature of Adjustment	New Lease Guidance Adoption Adjustment
Assets
Property and equipment, net	Derecognition - build-to-suit lease assets - building shell, cost	$	(53,880	)
	Derecognition - build-to-suit lease assets - building shell, accumulated depreciation		13,476
	Change of useful life - leasehold improvements, accumulated depreciation		(38,877	)
Finance lease right-of-use assets	Recognition - finance lease ROU assets		49,597
Other assets	Recognition - operating lease ROU assets		730
Liabilities
Accrued and other current liabilities	Derecognition - deferred rent, current		(619	)
	Derecognition - build-to-suit lease liabilities, current		(545	)
	Recognition - operating lease liabilities, current		404
Finance lease liabilities, current	Recognition - finance lease liabilities, current		11,499
Long-term portion of lease obligations	Derecognition - build-to-suit lease liabilities, non-current		(95,613	)
Deferred rent	Derecognition - deferred rent, non-current		(3,038	)
Finance lease liabilities, non-current	Recognition - finance lease liabilities, non-current		49,884
Other long-term liabilities	Recognition - operating lease liabilities, non-current		250
Stockholders’ equity
Accumulated deficit	Cumulative decrease to accumulated deficit	$	8,688

ASU 2018-02 [Member]

Schedule of Impacts Upon Adoption of New Guidance

The impacts, based on the aggregate portfolio approach, to the Company’s accumulated other comprehensive loss and accumulated deficit upon adoption of this guidance are as follows (in thousands):

	Accumulated Other Comprehensive Loss			Accumulated Deficit
Balance at December 31, 2018	$	(2,281	)	$	(715,827	)
Impact of change in accounting principle upon adoption of ASU 2018-02		611			(611	)
Opening balance as of January 1, 2019	$	(1,670	)	$	(716,438	)

Collaboration Agreements (Tables)

9 Months Ended

Sep. 30, 2019

Japan [Member]

Summary of Revenue Recognized under Agreement

Amounts recognized as revenue under the Japan Agreement were as follows (in thousands):

		Three Months Ended September 30,				Nine Months Ended September 30,
Agreement	Performance Obligation	2019		2018		2019		2018
Japan	License revenue	$	11,935	$	—	$	11,935	$	14,323
	Development revenue	$	537	$	474	$	1,151	$	2,065

Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations along with Associated Deferred Revenue

Japan Agreement	Cumulative Revenue Through September 30, 2019		Deferred Revenue at September 30, 2019		Total Consideration Through September 30, 2019
License	$	86,024	$	—	$	86,024
Development revenue		15,060		312		15,372
Total license and development revenue	$	101,084	$	312	$	101,396

Europe [Member]

Summary of Revenue Recognized under Agreement

Amounts recognized as revenue under the Europe Agreement were as follows (in thousands):

		Three Months Ended September 30,				Nine Months Ended September 30,
Agreement	Performance Obligation	2019		2018		2019		2018
Europe	License revenue	$	—	$	—	$	117,470	$	—
	Development revenue	$	2,996	$	4,658	$	24,463	$	14,384

Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations along with Associated Deferred Revenue

Europe Agreement	Cumulative Revenue Through September 30, 2019		Deferred Revenue at September 30, 2019			Total Consideration Through September 30, 2019
License	$	487,951	$	—		$	487,951
Development revenue		227,300		3,988			231,288
Total license and development revenue	$	715,251	$	3,988	*	$	719,239

_______________________________________________________________________________________________________

U.S./RoW and China [Member]

Summary of Revenue Recognized under Agreement

Amounts recognized as revenue under the U.S./RoW Agreement were as follows (in thousands):

		Three Months Ended September 30,				Nine Months Ended September 30,
Agreement	Performance Obligation	2019		2018		2019		2018
U.S. / RoW and China	License revenue	$	—	$	—	$	33,112	$	—
	Development revenue		17,106		23,895		59,872		74,096
	China performance obligation	$	19	$	—	$	19	$	—

Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations along with Associated Deferred Revenue

U.S. / RoW and China Agreements	Cumulative Revenue Through September 30, 2019		Deferred Revenue at September 30, 2019			Total Consideration Through September 30, 2019
License	$	327,275	$	—		$	327,275
Co-development, information sharing & committee services		468,509		11,317			479,826
China performance obligation		19		137,330			137,349
Total license and development revenue	$	795,803	$	148,647	*	$	944,450

_______________________________________________________________________________________________________

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2019

Fair Value Disclosures [Abstract]

Fair Values of Financial Assets Measured on Recurring Basis

The fair values of the Company’s financial assets that are measured on a recurring basis are as follows (in thousands):

	September 30, 2019
	Level 1		Level 2		Level 3		Total
US treasury notes and bills	$	226,590	$	175,450	$	—	$	402,040
Bond and mutual funds		10,748		—		—		10,748
Equity investments		251		—		—		251
Money market funds		105,822		—		—		105,822
Certificate of deposit		—		30,000		—		30,000
Total	$	343,411	$	205,450	$	—	$	548,861

	December 31, 2018
	Level 1		Level 2		Level 3		Total
US treasury notes and bills	$	292,317	$	224,953	$	—	$	517,270
Bond and mutual funds		10,484		—		—		10,484
Equity investments		234		—		—		234
Money market funds		541		—		—		541
Term deposit		—		80,000		—		80,000
Certificate of deposit		—		29,910		—		29,910
Total	$	303,576	$	334,863	$	—	$	638,439

Fair Values of Financial Liabilities Carried at Historical Cost

The fair values of the Company’s financial liabilities that are carried at historical cost are as follows (in thousands):

	September 30, 2019
	Level 1		Level 2		Level 3		Total
Lease obligations	$	—	$	—	$	1,645	$	1,645

	December 31, 2018
	Level 1		Level 2		Level 3		Total
Lease obligations	$	—	$	—	$	98,105	$	98,105

Leases (Tables)

9 Months Ended

Sep. 30, 2019

Leases [Abstract]

Schedule of Lease Assets and Related Lease Liabilities

The Company’s lease assets and related lease liabilities were as follows (in thousands):

	Balance Sheet Line Item	September 30, 2019
Assets
Finance:
Right-of-use assets - cost		$	49,784
Accumulated amortization			(7,720	)
Finance lease right-of-use assets, net	Finance lease right-of-use assets		42,064
Operating:
Right-of-use assets - cost			2,723
Accumulated amortization			(531	)
Operating lease right-of-use assets, net	Other assets		2,192
Total lease assets		$	44,256

Liabilities
Current:
Finance lease liabilities	Finance lease liabilities, current	$	12,149
Operating lease liabilities	Accrued and other current liabilities		998
Non-current:
Finance lease liabilities	Finance lease liabilities, non-current		40,713
Operating lease liabilities	Other long-term liabilities		1,133
Total lease liabilities		$	54,993

Components of Lease Expense

The components of lease expense were as follows (in thousands):

	Statement of Operations Line Item	Three Months Ended September 30, 2019			Nine Months Ended September 30, 2019
Finance lease cost:
Amortization of right-of-use assets	Selling, general and administrative expenses	$	2,580		$	7,720
Interest on lease liabilities	Interest expense		578			1,826
Operating lease cost	Research and development, Selling, general and administrative expenses		290			579
Sublease income	Selling, general and administrative expenses		(310	)		(1,135	)
Total lease cost		$	3,138		$	8,990

Schedule of Supplemental Cash Flow Information Related to Leases

Supplemental cash flow information related to leases were as follows (in thousands):

	Nine Months Ended September 30, 2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$	540
Operating cash flows from finance leases		1,640
Financing cash flows from finance leases		8,810
Right-of-use assets obtained in exchange for new lease liabilities:
Finance leases		49,784
Operating leases	$	2,723

Schedule of Lease Term and Discount Rate

Lease term and discount rate were as follows at September 30, 2019:

	September 30, 2019
Weighted-average remaining lease term (years):
Finance leases		3.8
Operating leases		2.3
Weighted-average discount rate:
Finance leases		4.43	%
Operating leases		4.75	%

Schedule of Maturities of Finance and Operating Leases Liabilities

Maturities of lease liabilities are as follows:

Year Ending	Finance Leases			Operating Leases
2019 (Remaining three month period)	$	3,466		$	280
2020		14,060			1,013
2021		13,675			651
2022		13,878			300
2023		12,523			—
Total future lease payments		57,602			2,244
Less: Interest		(4,740	)		(113	)
Present value of lease liabilities	$	52,862		$	2,131

Schedule of Future Minimum Lease Payments Under all Non-Cancelable Operating Lease Obligations

Future minimum lease payments under all non-cancelable operating lease obligations as of December 31, 2018 were as follows (in thousands):

Year Ending	Operating Leases
2019	$	444
2020		232
2021		25
2022		16
2023		—
Total minimum payments	$	717

Schedule of Future Minimum Lease Payments on Consolidated Basis Under Company's Facility Financing Lease Obligations

Future minimum lease payments, on a consolidated basis, under the Company’s facility lease financing obligations as of December 31, 2018 were as follows (in thousands):

Year Ending	Lease financing obligations
2019	$	14,379
2020		14,664
2021		14,179
2022		14,335
2023		12,872
Total minimum payments	$	70,429

Balance Sheet Components (Tables)

9 Months Ended

Sep. 30, 2019

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Schedule of Cash and Cash Equivalents

Cash and cash equivalents consisted of the following (in thousands):

	September 30, 2019		December 31, 2018
Cash	$	90,770	$	38,783
US treasury notes and bills		—		49,934
Money market funds		105,822		541
Total cash and cash equivalents	$	196,592	$	89,258

Summary of Amortized Cost, Gross Unrealized Holding Gains or Losses, and Fair Value of Available-for-Sale Investments

	September 30, 2019
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Fair Value
US treasury notes and bills	$	401,377	$	688	$	(25	)	$	402,040
Certificates of deposit		30,000		—		—			30,000
Bond and mutual funds		10,668		80		—			10,748
Equity investments		125		126		—			251
Total investments	$	442,170	$	894	$	(25	)	$	443,039

	December 31, 2018
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Fair Value
US treasury notes and bills	$	467,296	$	109	$	(69	)	$	467,336
Term deposit		80,000		—		—			80,000
Certificates of deposit		30,000		—		(90	)		29,910
Bond and mutual funds		10,464		20		—			10,484
Equity investments		125		109		—			234
Total investments	$	587,885	$	238	$	(159	)	$	587,964

Schedule of Inventory

Inventories consisted of the following (in thousands):

	September 30, 2019
Raw materials	$	658
Work-in-progress		1,155
Finished goods		3,095
Total inventories	$	4,908

Schedule of Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consisted of the following (in thousands):

	September 30, 2019			December 31, 2018
Unbilled contract assets	$	180,000		$	—
Deferred revenues from associated contracts		(53,988	)		—
Net unbilled contract assets		126,012			—
Prepaid assets		4,051			2,705
Other current assets		3,652			2,224
Total prepaid expenses and other current assets	$	133,715		$	4,929

Schedule of Property and Equipment

Property and equipment consisted of the following (in thousands):

	September 30, 2019			December 31, 2018
Leasehold improvements	$	101,339		$	101,200
Building shell		—			53,880
Laboratory equipment		16,932			16,405
Machinery		8,691			8,382
Computer equipment		7,227			6,473
Furniture and fixtures		5,789			5,690
Construction in progress		2,332			367
Total property and equipment	$	142,310		$	192,397
Less: accumulated depreciation		(99,102	)		(65,199	)
Property and equipment, net	$	43,208		$	127,198

Schedule of Accrued Liabilities

Accrued liabilities consisted of the following (in thousands):

	September 30, 2019		December 31, 2018
Preclinical and clinical trial accruals	$	41,546	$	35,413
Payroll and related accruals		17,604		21,430
Property taxes and other		2,389		1,095
Professional services		4,063		2,648
Other		5,223		5,537
Total accrued liabilities	$	70,825	$	66,123

Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Allocated Stock-Based Compensation Expense

Stock-based compensation expense was allocated to research and development and selling, general and administrative expense as follows (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
Research and development	$	10,185	$	8,465	$	30,214	$	22,729
Selling, general and administrative		4,608		5,858		18,651		15,703
Total stock-based compensation expense	$	14,793	$	14,323	$	48,865	$	38,432

Schedule of Assumptions used to Estimate Fair Value of Stock Options Granted and Purchases under 2014 Employee Share Purchase Plan

	Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019			2018
Stock Options
Expected term (in years)		5.3			5.3			5.3			5.4
Expected volatility		67.8	%		68.1	%		67.9	%		67.8	%
Risk-free interest rate		1.7	%		2.9	%		2.4	%		2.7	%
Expected dividend yield		—			—			—			—
Weighted average estimated fair value	$	25.17		$	35.99		$	32.44		$	32.37

ESPPs
Expected term (in years)	0.5 - 2.0			0.5 - 2.0			0.5 - 2.0			0.5 - 2.0
Expected volatility	48.1 - 62.1		%	47.3 - 72.8		%	48.1 - 62.1		%	47.3 - 75.3		%
Risk-free interest rate	1.6 - 2.9		%	1.0 - 2.6		%	1.3 - 2.9		%	0.8 - 2.6		%
Expected dividend yield		—			—			—			—
Weighted average estimated fair value	$	19.27		$	20.10		$	19.53		$	15.27

Significant Accounting Policies - Additional Information (Detail) shares in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019 shares	Sep. 30, 2018 shares	Sep. 30, 2019 Segment shares	Sep. 30, 2018 shares	Dec. 31, 2017
Accounting Policies [Abstract]
Number of operating segment \| Segment			1
Short term investments maturity			12 months
Anti-dilutive shares \| shares	9.2	9.3	3.6	9.1
U.S. federal statutory income tax rate			21.00%		35.00%

Significant Accounting Policies - Summary of Reconciliation of Basic and Diluted Net Income (Loss) Per Share Calculation (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share [Abstract]
Net income (loss)	$ (49,439)	$ (42,556)	$ 21,153	$ (107,373)
Weighted average number of common shares used to calculate net income (loss) per share:
Basic	87,007	84,508	86,390	83,713
Dilutive effect of potential common shares	0	0	5,605	0
Diluted	87,007	84,508	91,995	83,713
Net income (loss) per share:
Basic	$ (0.57)	$ (0.50)	$ 0.24	$ (1.28)
Diluted	$ (0.57)	$ (0.50)	$ 0.23	$ (1.28)

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

+ References

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+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
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+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Summary of Significant Accounting Policies - Schedule of Impacts to Condensed Consolidated Balance Sheet Upon Adoption of 842 Guidance (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Assets
Property and equipment, net	$ 43,208	$ 127,198
Finance lease right-of-use assets	42,064	0
Liabilities, stockholders’ equity and non-controlling interests
Finance lease liabilities, current	12,149	0
Deferred rent	0	3,038
Finance lease liabilities, non-current	40,713	0
Accumulated deficit	(686,597)	$ (715,827)
Derecognition Build to Suit Lease Assets [Member] \| Building Shell [Member]
Assets
Property and equipment, net	(53,880)
Derecognition Build to Suit Lease Assets Accumulated Depreciation [Member] \| Building Shell [Member]
Assets
Property and equipment, net	13,476
Leasehold Improvements Accumulated Depreciation [Member]
Assets
Property and equipment, net	(38,877)
Recognition Finance Lease Assets [Member]
Assets
Finance lease right-of-use assets	49,597
Recognition Operating Lease Assets [Member]
Assets
Other assets	730
Derecognition Deferred Rent Current [Member]
Liabilities, stockholders’ equity and non-controlling interests
Accrued and other current liabilities	(619)
Derecognition Build to Suit Lease Liabilities Current [Member]
Liabilities, stockholders’ equity and non-controlling interests
Accrued and other current liabilities	(545)
Recognition Operating Lease Liabilities Current [Member]
Liabilities, stockholders’ equity and non-controlling interests
Accrued and other current liabilities	404
Recognition Finance Lease Liabilities Current [Member]
Liabilities, stockholders’ equity and non-controlling interests
Finance lease liabilities, current	11,499
Derecognition Build to Suit Lease Liabilities Non Current [Member]
Liabilities, stockholders’ equity and non-controlling interests
Long-term portion of lease obligations	(95,613)
Derecognition Deferred Rent Non Current [Member]
Liabilities, stockholders’ equity and non-controlling interests
Deferred rent	(3,038)
Recognition Finance Lease Liabilities Non Current [Member]
Liabilities, stockholders’ equity and non-controlling interests
Finance lease liabilities, non-current	49,884
Recognition Operating Lease Liabilities Non Current [Member]
Liabilities, stockholders’ equity and non-controlling interests
Other long-term liabilities	250
Cumulative Decrease to Accumulated Deficit [Member]
Liabilities, stockholders’ equity and non-controlling interests
Accumulated deficit	$ 8,688

Summary of Significant Accounting Policies - Schedule of Impacts to Accumulated Other Comprehensive Loss and Accumulated Deficit Upon Adoption of Guidance (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Accounting Policy [Line Items]
Accumulated other comprehensive loss	$ (224)		$ (2,281)
Accumulated deficit	$ (686,597)		$ (715,827)
ASU 2018-02 [Member]
Accounting Policy [Line Items]
Accumulated other comprehensive loss		$ (1,670)
Accumulated deficit		(716,438)
Impact of change in accounting principle upon adoption of ASU 2018-02 [Member] \| ASU 2018-02 [Member]
Accounting Policy [Line Items]
Accumulated other comprehensive loss		611
Accumulated deficit		$ (611)

Collaboration Agreements - Astellas Agreements - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended			9 Months Ended	12 Months Ended	35 Months Ended	45 Months Ended
	Sep. 30, 2019	Apr. 30, 2006	Jun. 30, 2005	Sep. 30, 2019	Dec. 31, 2018	Feb. 28, 2009	Feb. 28, 2009
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Unbilled contract asset	$ 180,000			$ 180,000	$ 0
Europe [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Unbilled contract asset	130,000			130,000
Astellas Agreement [Member] \| Japan [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront, non-contingent and time-based payments received							$ 40,100
Potential milestone payments	12,500		$ 132,500
Commercial sales milestone			15,000
Aggregate consideration received	77,600			77,600
Transaction price and allocated to performance obligations	12,500			12,500
Astellas Agreement [Member] \| Japan [Member] \| Clinical and Development Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			22,500
Astellas Agreement [Member] \| Japan [Member] \| Regulatory Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			$ 95,000
Astellas Agreement [Member] \| Europe [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront, non-contingent and time-based payments received						$ 320,000
Potential milestone payments		$ 425,000
Aggregate consideration received	410,000			410,000
Transaction price and allocated to performance obligations	130,000			$ 130,000
Percentage of joint development costs committed to fund		50.00%
Additional consideration based on net sales description				low 20% range
Estimated joint development extended service period					2023
Revenue during period from performance obligations	129,000			$ 129,000
Unbilled contract asset	$ 130,000			$ 130,000
Astellas Agreement [Member] \| Europe [Member] \| Clinical and Development Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments		$ 90,000
Astellas Agreement [Member] \| Europe [Member] \| Regulatory Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments		$ 335,000

Collaboration Agreements - AstraZeneca Agreements - Additional Information 1 (Detail) - USD ($) $ in Thousands				9 Months Ended	12 Months Ended
	Dec. 29, 2018	Dec. 17, 2018	Jul. 30, 2013	Sep. 30, 2019	Dec. 31, 2015	Jun. 30, 2019	Dec. 31, 2018
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Unbilled contract asset				$ 180,000			$ 0
AstraZeneca Agreements [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Transaction price and allocated to performance obligations						$ 50,000
Revenue during period from performance obligations				42,100
Unbilled contract asset				50,000
AstraZeneca Agreements [Member] \| U.S./RoW [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront, non-contingent, non-refundable and time-based payments			$ 374,000
Potential milestone payments			875,000
Commercial sales milestone			325,000
Aggregate consideration received				389,000
Unbilled contract asset				50,000
AstraZeneca Agreements [Member] \| U.S./RoW [Member] \| Clinical and Development Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			65,000
AstraZeneca Agreements [Member] \| U.S./RoW [Member] \| Regulatory Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			325,000
AstraZeneca Agreements [Member] \| U.S./RoW [Member] \| Deferred Approval Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			160,000
AstraZeneca Agreements [Member] \| U.S./RoW [Member] \| Development Milestones [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Receipt of development milestone payment					$ 15,000
AstraZeneca Agreements [Member] \| China [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			348,500
Aggregate consideration received				$ 55,200
Proceeds from upfront, non-contingent and non-refundable payments			28,200
Commercial sales and other events milestone			187,500
Estimated joint development extended service period				2024
Milestone payment, revenue recognition	$ 6,000	$ 6,000
AstraZeneca Agreements [Member] \| China [Member] \| Clinical and Development Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			15,000
AstraZeneca Agreements [Member] \| China [Member] \| Regulatory Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			$ 146,000

Collaboration Agreements - Summary of Revenue Recognized under Agreement (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	$ 33,174	$ 29,027	$ 248,603	$ 104,903
License Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	11,935	0	162,517	14,323
Development Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	20,660	29,027	85,507	90,580
Astellas Agreement [Member] \| License Revenue [Member] \| Japan [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	11,935	0	11,935	14,323
Astellas Agreement [Member] \| License Revenue [Member] \| Europe [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	0	0	117,470	0
Astellas Agreement [Member] \| Development Revenue [Member] \| Japan [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	537	474	1,151	2,065
Astellas Agreement [Member] \| Development Revenue [Member] \| Europe [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	2,996	4,658	24,463	14,384
AstraZeneca Agreements [Member] \| China [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	19	0	19	0
AstraZeneca Agreements [Member] \| License Revenue [Member] \| U.S./RoW and China [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	0	0	33,112	0
AstraZeneca Agreements [Member] \| Development Revenue [Member] \| U.S./RoW and China [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	$ 17,106	$ 23,895	$ 59,872	$ 74,096

Collaboration Agreements - Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations along with Associated Deferred Revenue (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Deferred Revenue	$ 53,988	$ 0
Astellas Agreement [Member] \| Japan [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	101,084
Deferred Revenue	312
Total Consideration	101,396
Astellas Agreement [Member] \| Japan [Member] \| Development Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	15,060
Deferred Revenue	312
Total Consideration	15,372
Astellas Agreement [Member] \| Japan [Member] \| License Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	86,024
Deferred Revenue	0
Total Consideration	86,024
Astellas Agreement [Member] \| Europe [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	715,251
Deferred Revenue	3,988
Total Consideration	719,239
Astellas Agreement [Member] \| Europe [Member] \| Development Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	227,300
Deferred Revenue	3,988
Total Consideration	231,288
Astellas Agreement [Member] \| Europe [Member] \| License Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	487,951
Deferred Revenue	0
Total Consideration	487,951
AstraZeneca Agreements [Member] \| U.S./RoW and China [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	795,803
Deferred Revenue	148,647
Total Consideration	944,450
AstraZeneca Agreements [Member] \| U.S./RoW and China [Member] \| License Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	327,275
Deferred Revenue	0
Total Consideration	327,275
AstraZeneca Agreements [Member] \| U.S./RoW and China [Member] \| Co-development, information sharing & committee services [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	468,509
Deferred Revenue	11,317
Total Consideration	479,826
AstraZeneca Agreements [Member] \| U.S./RoW and China [Member] \| China performance obligation [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	19
Deferred Revenue	137,330
Total Consideration	$ 137,349

Collaboration Agreements - Summary of Revenue Recognized Under the Collaboration Agreements - Additional Information 4 (Detail) $ in Millions	3 Months Ended
	Sep. 30, 2019 USD ($)
Japan [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Remainder of transaction price, variable consideration from estimated future co-development billing	$ 0.2
Japan [Member] \| Astellas Agreement [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Changes in revenue due to prior period adjustment of performance obligations	12.3
Europe [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Remainder of transaction price, variable consideration from estimated future co-development billing	42.4
Europe [Member] \| Astellas Agreement [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Changes in revenue due to prior period adjustment of performance obligations	2.9
U.S./RoW and China [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Remainder of transaction price, variable consideration from estimated future co-development billing	186.6
U.S./RoW and China [Member] \| AstraZeneca Agreements [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Changes in revenue due to prior period adjustment of performance obligations	$ 3.5

Collaboration Agreements - Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations along with Associated Deferred Revenue (Parenthetical) (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Unbilled contract asset	$ 180,000	$ 0
Deferred revenue	53,988	0
Net unbilled contract asset	126,012	0
Long-term deferred revenue	98,708	$ 136,109
Europe [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Unbilled contract asset	130,000
Astellas Agreement [Member] \| Europe [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Unbilled contract asset	130,000
Deferred revenue	3,988
Astellas Agreement [Member] \| Europe [Member] \| Prepaid Expenses and Other Current Assets [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Net unbilled contract asset	126,000
AstraZeneca Agreements [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Unbilled contract asset	50,000
AstraZeneca Agreements [Member] \| U.S./RoW [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Unbilled contract asset	50,000
Deferred revenue	148,600
Net unbilled contract asset	50,000
Long-term deferred revenue	$ 98,600

Collaboration Agreements - Product Revenue - Additional Information 4 (Detail) $ in Millions	3 Months Ended
	Sep. 30, 2019 USD ($)
Product Revenue [Member] \| China [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Contract with customer, liability, revenue recognized	$ 0.6

Collaboration Agreements - Deferred Revenue - Additional Information (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Contract with Customer, Liability [Abstract]
Deferred revenue	$ 53,988	$ 0
AstraZeneca Agreements [Member] \| China [Member]
Contract with Customer, Liability [Abstract]
Deferred revenue	$ 700

Fair Value Measurements - Fair Values of Financial Liabilities Carried at Historical Cost (Detail) - Lease obligations [Member] - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities fair value disclosure	$ 1,645	$ 98,105
Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities fair value disclosure	0	0
Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities fair value disclosure	0	0
Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities fair value disclosure	$ 1,645	$ 98,105

Fair Value Measurements - Additional Information (Detail) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Lease payment liability	$ 52,862,000
Transfers of assets from level 1 to 2	0	$ 0
Transfers of assets from level 2 to 1	0	0
Transfers of liabilities from level 1 to 2	0	0
Transfers of liabilities from level 2 to 1	0	0
Transfers of assets into level 3	0	0
Transfers of assets out of level 3	0	0
Transfers of liabilities into level 3	0	0
Transfers of liabilities out of level 3	$ 0	0
Shorenstein Properties LLC [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Lease commencement date	2008
Lease payment liability	$ 5,000,000.0
Remaining lease term	2023
Building [Member] \| Shorenstein Properties LLC [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Lease maximum expansion period	31 months
Lease obligations [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities fair value disclosure	$ 1,645,000	98,105,000
Lease obligations [Member] \| Long-term property lease [Member] \| Shorenstein Properties LLC [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities fair value disclosure	$ 1,600,000
Lease obligations [Member] \| Building [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities fair value disclosure		$ 96,200,000

Leases - Additional Information (Detail) - Lease	9 Months Ended	12 Months Ended
Leases - Additional Information (Detail) - Lease	Sep. 30, 2019	Dec. 31, 2013	Dec. 31, 2006
Minimum [Member]
Lessee Lease Description [Line Items]
Lessee, operating lease, lease term	2 years
Maximum [Member]
Lessee Lease Description [Line Items]
Lessee, operating lease, lease term	4 years
Shorenstein Properties LLC [Member]
Lessee Lease Description [Line Items]
Lessee, finance lease, initial lease term			15 years
Lessee, finance lease, expiration period			2023
Lessee, finance lease, option to extend the additional lease term			10 years
Lessee, finance lease, additional lease expiration period			2033
Percentage increases on each anniversary of rent commencement date			2.00%
Lessee, finance lease, existence of option to extend			true
Lessee, finance lease, option to extend	The Company has an option to extend the lease for an additional 10 years through 2033.
Beijing Economic-Technological Development Area [Member]
Lessee Lease Description [Line Items]
Lessee, finance lease, initial lease term		8 years
Lessee, finance lease, expiration period		2021
Lessee, finance lease, existence of option to extend		false
Building [Member]
Lessee Lease Description [Line Items]
Number of finance leases	2
Number of operating leases	6
Office Equipment [Member] \| Minimum [Member]
Lessee Lease Description [Line Items]
Lessee, operating lease, lease term	2 years
Office Equipment [Member] \| Maximum [Member]
Lessee Lease Description [Line Items]
Lessee, operating lease, lease term	5 years

Leases - Schedule of Lease Assets and Related Lease Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Leases [Abstract]
Right-of-use assets - cost	$ 49,784
Accumulated amortization	(7,720)
Finance lease right-of-use assets, net	42,064	$ 0
Right-of-use assets - cost	2,723
Accumulated amortization	(531)
Operating lease right-of-use assets, net	2,192
Total lease assets	44,256
Finance lease liabilities	12,149	0
Operating lease liabilities	998
Finance lease liabilities	40,713	$ 0
Operating lease liabilities	1,133
Total lease liabilities	$ 54,993

Leases - Components of Lease Expense (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2018
Finance lease cost:
Amortization of right-of-use assets	$ 2,580	$ 7,720	$ 0
Interest on lease liabilities	578	1,826
Operating lease cost	290	579
Sublease income	(310)	(1,135)
Total lease cost	$ 3,138	$ 8,990

Leases - Schedule of Supplemental Cash Flow Information Related to Leases (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 540
Operating cash flows from finance leases	1,640
Financing cash flows from finance leases	8,810	$ 0
Right-of-use assets obtained in exchange for new lease liabilities:
Finance leases	49,784
Operating leases	$ 2,723

Leases - Schedule of Lease Term and Discount Rate (Detail)	Sep. 30, 2019
Weighted-average remaining lease term (years):
Finance leases	3 years 9 months 18 days
Operating leases	2 years 3 months 18 days
Weighted-average discount rate:
Finance leases	4.43%
Operating leases	4.75%

Leases - Schedule of Maturities of Lease Liabilities (Detail) $ in Thousands	Sep. 30, 2019 USD ($)
Finance Leases
2019 (Remaining three month period)	$ 3,466
2020	14,060
2021	13,675
2022	13,878
2023	12,523
Total future lease payments	57,602
Less: Interest	(4,740)
Present value of lease liabilities	52,862
Operating Leases
2019 (Remaining three month period)	280
2020	1,013
2021	651
2022	300
2023	0
Total future lease payments	2,244
Less: Interest	(113)
Present value of lease liabilities	$ 2,131

Leases - Schedule of Future Minimum Lease Payments Under all Non-Cancelable Operating Lease Obligations (Detail) $ in Thousands	Dec. 31, 2018 USD ($)
Leases [Abstract]
2019	$ 444
2020	232
2021	25
2022	16
2023	0
Total minimum payments	$ 717

Leases - Schedule of Future Minimum Lease Payments on Consolidated Basis Under Company's Facility Financing Lease Obligations (Detail) $ in Thousands	Dec. 31, 2018 USD ($)
Leases [Abstract]
2019	$ 14,379
2020	14,664
2021	14,179
2022	14,335
2023	12,872
Total minimum payments	$ 70,429

Balance Sheet Components - Schedule of Cash and Cash Equivalents (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Cash And Cash Equivalents [Abstract]
Cash	$ 90,770	$ 38,783
US treasury notes and bills	0	49,934
Money market funds	105,822	541
Total cash and cash equivalents	$ 196,592	$ 89,258

Balance Sheet Components - Additional Information (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) Milestone	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Cash and cash equivalents	$ 196,592,000		$ 196,592,000		$ 89,258,000
Contractual maturities of available-for-sale investments			1 year
Other-than-temporary impairment loss	0	$ 0	$ 0	$ 0
Provision to write-down excess and obsolete inventory	0		$ 0
Number of regulatory milestones \| Milestone			2
Unbilled contract assets	180,000,000		$ 180,000,000		0
Building shell cost	142,310,000		142,310,000		192,397,000
Accumulated depreciation	99,102,000		99,102,000		65,199,000
Building shell [Member]
Schedule of Available-for-sale Securities [Line Items]
Building shell cost	0		0		53,880,000
Building [Member] \| Build to suit arrangements [Member]
Schedule of Available-for-sale Securities [Line Items]
Accumulated depreciation					13,500,000
Leasehold improvements [Member]
Schedule of Available-for-sale Securities [Line Items]
Building shell cost	101,339,000		101,339,000		101,200,000
Leasehold improvements [Member] \| Accounting standards update 2016-02 [Member]
Schedule of Available-for-sale Securities [Line Items]
Accumulated depreciation	38,900,000		38,900,000
Europe [Member]
Schedule of Available-for-sale Securities [Line Items]
Unbilled contract assets	130,000,000.0		130,000,000.0
Astellas Agreement [Member] \| Europe [Member]
Schedule of Available-for-sale Securities [Line Items]
Unbilled contract assets	130,000,000.0		130,000,000.0
AstraZeneca Agreements [Member]
Schedule of Available-for-sale Securities [Line Items]
Unbilled contract assets	50,000,000.0		50,000,000.0
AstraZeneca Agreements [Member] \| U.S./RoW [Member]
Schedule of Available-for-sale Securities [Line Items]
Unbilled contract assets	50,000,000.0		50,000,000.0
Foreign subsidiaries [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and cash equivalents	$ 18,100,000		$ 18,100,000		$ 21,900,000

Balance Sheet Components - Summary of Amortized Cost, Gross Unrealized Holding Gains or Losses, and Fair Value of Available-for-Sale Investments (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 442,170	$ 587,885
Gross Unrealized Holding Gains	894	238
Gross Unrealized Holding Losses	(25)	(159)
Fair Value	443,039	587,964
US treasury notes and bills [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	401,377	467,296
Gross Unrealized Holding Gains	688	109
Gross Unrealized Holding Losses	(25)	(69)
Fair Value	402,040	467,336
Term deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		80,000
Gross Unrealized Holding Gains		0
Gross Unrealized Holding Losses		0
Fair Value		80,000
Certificate of deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	30,000	30,000
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	0	(90)
Fair Value	30,000	29,910
Bond and mutual funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	10,668	10,464
Gross Unrealized Holding Gains	80	20
Gross Unrealized Holding Losses	0	0
Fair Value	10,748	10,484
Equity investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	125	125
Gross Unrealized Holding Gains	126	109
Gross Unrealized Holding Losses	0	0
Fair Value	$ 251	$ 234

Balance Sheet Components - Schedule of Inventory (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Schedule Of Investments [Abstract]
Raw materials			$ 658
Work-in-progress			1,155
Finished goods			3,095
Total inventories	$ 4,908	$ 0	$ 4,908

Balance Sheet Components - Schedule of Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Prepaid Expense And Other Assets Current [Abstract]
Unbilled contract assets	$ 180,000	$ 0
Deferred revenues from associated contracts	(53,988)	0
Net unbilled contract assets	126,012	0
Prepaid assets	4,051	2,705
Other current assets	3,652	2,224
Total prepaid expenses and other current assets	$ 133,715	$ 4,929

Balance Sheet Components - Schedule of Property and Equipment (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 142,310	$ 192,397
Less: accumulated depreciation	(99,102)	(65,199)
Property and equipment, net	43,208	127,198
Leasehold improvements [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	101,339	101,200
Building shell [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	0	53,880
Laboratory Equipment [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	16,932	16,405
Machinery [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	8,691	8,382
Computer Equipment [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	7,227	6,473
Furniture and Fixtures [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	5,789	5,690
Construction in progress [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 2,332	$ 367

Balance Sheet Components - Schedule of Accrued Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Accrued Liabilities Current [Abstract]
Preclinical and clinical trial accruals	$ 41,546	$ 35,413
Payroll and related accruals	17,604	21,430
Property taxes and other	2,389	1,095
Professional services	4,063	2,648
Other	5,223	5,537
Total accrued liabilities	$ 70,825	$ 66,123

Stock-Based Compensation - Schedule of Allocated Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 14,793	$ 14,323	$ 48,865	$ 38,432
Research and development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	10,185	8,465	30,214	22,729
Selling, general and administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 4,608	$ 5,858	$ 18,651	$ 15,703

Stock-Based Compensation - Schedule of Assumptions used to Estimate Fair Value of Stock Options Granted and Purchases under 2014 Employee Share Purchase Plan (Detail) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Employee stock options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	5 years 3 months 18 days	5 years 3 months 18 days	5 years 3 months 18 days	5 years 4 months 24 days
Expected volatility	67.80%	68.10%	67.90%	67.80%
Risk-free interest rate	1.70%	2.90%	2.40%	2.70%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Weighted average estimated fair value	$ 25.17	$ 35.99	$ 32.44	$ 32.37
2014 Employee Share Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility, minimum	48.10%	47.30%	48.10%	47.30%
Expected volatility, maximum	62.10%	75.30%	62.10%	75.30%
Risk-free interest rate, minimum	1.30%	0.80%	1.30%	0.80%
Risk-free interest rate, maximum	2.90%	2.60%	2.90%	2.60%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Weighted average estimated fair value	$ 19.27	$ 20.10	$ 19.53	$ 15.27
2014 Employee Share Purchase Plan [Member] \| Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 months	6 months	6 months	6 months
2014 Employee Share Purchase Plan [Member] \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	2 years	2 years	2 years	2 years

Related Party Transactions - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Related Party Transaction [Line Items]
Accounts receivable from related party	$ 17,662,000		$ 17,662,000		$ 47,210,000
Accrued liabilities to related party	954,000		954,000		444,000
Unbilled contract asset	180,000,000		180,000,000		0
Due from Related Parties, Current	126,012,000		126,012,000		0
Net unbilled contract asset	126,012,000		126,012,000		0
Deferred Revenue	53,988,000		53,988,000		0
Europe [Member]
Related Party Transaction [Line Items]
Unbilled contract asset	130,000,000.0		130,000,000.0
Astellas Agreement [Member] \| Europe [Member]
Related Party Transaction [Line Items]
Unbilled contract asset	130,000,000.0		130,000,000.0
Deferred Revenue	3,988,000		3,988,000
Astellas [Member] \| Europe [Member]
Related Party Transaction [Line Items]
Unbilled contract asset	130,000,000.0		130,000,000.0
Net unbilled contract asset	126,000,000.0		126,000,000.0
Deferred Revenue	4,000,000.0		4,000,000.0
Astellas [Member] \| Collaborative Arrangement [Member]
Related Party Transaction [Line Items]
Revenue related to collaboration agreements	15,500,000	$ 5,100,000	155,000,000.0	$ 30,800,000
Expense related to collaboration agreements	900,000	$ 400,000	2,200,000	$ 1,100,000
Accounts receivable from related party	17,700,000		17,700,000		47,200,000
Accrued liabilities to related party	1,700,000		1,700,000		400,000
Astellas [Member] \| Astellas Agreement [Member] \| Milestone Payment [Member]
Related Party Transaction [Line Items]
Accrued liabilities to related party	$ 12,500,000		$ 12,500,000
Astellas [Member] \| Astellas Agreement [Member] \| Active Pharmaceutical Ingredients Shipment [Member]
Related Party Transaction [Line Items]
Accrued liabilities to related party					$ 43,800,000

Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2019	Oct. 31, 2019
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Trading Symbol	FGEN
Entity Registrant Name	FIBROGEN INC
Entity Central Index Key	0000921299
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Title of 12(b) Security	Common Stock, $0.01 par value
Security Exchange Name	NASDAQ
Entity File Number	1-36740
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	77-0357827
Entity Address, Address Line One	409 Illinois Street
Entity Address, City or Town	San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94158
City Area Code	415
Local Phone Number	978-1200
Document Quarterly Report	true
Document Transition Report	false
Entity Common Stock Shares Outstanding		87,250,064

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 196,592	$ 89,258
Short-term investments	432,040	532,144
Accounts receivable ($17,662 and $47,210 from a related party)	19,225	63,684
Inventories	4,908	0
Prepaid expenses and other current assets ($126,012 and $0 from a related party)	133,715	4,929
Total current assets	786,480	690,015
Restricted time deposits	4,145	4,145
Long-term investments	10,999	55,820
Property and equipment, net	43,208	127,198
Finance lease right-of-use assets	42,064	0
Other assets	7,068	3,420
Total assets	893,964	880,598
Current liabilities:
Accounts payable ($730 and $0 to a related party)	4,055	9,139
Accrued and other current liabilities ($954 and $444 to a related party)	70,825	66,123
Deferred revenue	257	13,771
Finance lease liabilities, current	12,149	0
Total current liabilities	87,286	89,033
Long-term portion of lease obligations	1,242	97,157
Product development obligations	16,256	16,798
Deferred rent	0	3,038
Deferred revenue, net of current	98,708	136,109
Finance lease liabilities, non-current	40,713	0
Other long-term liabilities	36,041	9,993
Total liabilities	280,246	352,128
Commitments and Contingencies
Stockholders’ equity:
Preferred stock, $0.01 par value; 125,000 shares authorized; no shares issued and outstanding at September 30, 2019 and December 31, 2018	0	0
Common stock, $0.01 par value; 225,000 shares authorized at September 30, 2019 and December 31, 2018; 87,211 and 85,432 shares issued and outstanding at September 30, 2019 and December 31, 2018	872	854
Additional paid-in capital	1,280,396	1,226,453
Accumulated other comprehensive loss	(224)	(2,281)
Accumulated deficit	(686,597)	(715,827)
Total stockholders’ equity	594,447	509,199
Non-controlling interests	19,271	19,271
Total equity	613,718	528,470
Total liabilities, stockholders’ equity and non-controlling interests	$ 893,964	$ 880,598

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Accounts receivable from related party	$ 17,662,000	$ 47,210,000
Prepaid expenses and other current assets from related party	126,012,000	0
Accounts payable to related party	730,000	0
Accrued and other current liabilities to related party	$ 954,000	$ 444,000
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	125,000,000	125,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	225,000,000	225,000,000
Common stock, shares issued	87,211,000	85,432,000
Common stock, shares outstanding	87,211,000	85,432,000

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenue:
Total revenue	$ 33,174	$ 29,027	$ 248,603	$ 104,903
Operating costs and expenses:
Cost of goods sold	$ 242	$ 0	$ 242	$ 0
Cost, Product and Service [Extensible List]	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember	us-gaap:ProductMember
Research and development	$ 49,963	$ 56,443	$ 152,467	$ 165,555
Selling, general and administrative	35,823	15,356	84,772	45,961
Total operating costs and expenses	86,028	71,799	237,481	211,516
Income (loss) from operations	(52,854)	(42,772)	11,122	(106,613)
Interest and other, net
Interest expense	(702)	(2,739)	(2,209)	(8,257)
Interest income and other, net	4,193	3,079	12,496	7,796
Total interest and other, net	3,491	340	10,287	(461)
Income (loss) before income taxes	(49,363)	(42,432)	21,409	(107,074)
Provision for income taxes	76	124	256	299
Net income (loss)	$ (49,439)	$ (42,556)	$ 21,153	$ (107,373)
Net income (loss) per share:
Basic	$ (0.57)	$ (0.50)	$ 0.24	$ (1.28)
Diluted	$ (0.57)	$ (0.50)	$ 0.23	$ (1.28)
Weighted average number of common shares used to calculate net income (loss) per share:
Basic	87,007	84,508	86,390	83,713
Diluted	87,007	84,508	91,995	83,713
License Revenue [Member]
Revenue:
Total revenue	$ 11,935	$ 0	$ 162,517	$ 14,323
Development and Other Revenue [Member]
Revenue:
Total revenue	20,660	29,027	85,507	90,580
Product Revenue [Member]
Revenue:
Total revenue	$ 579	$ 0	$ 579	$ 0

Condensed Consolidated Statements of Operations (Unaudited) (Parenthetical) - Astellas Agreement [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Collaboration services and other revenue from a related party	$ 3,533	$ 5,131	$ 25,615	$ 16,448
License and milestone revenue from a related party	$ 11,935	$ 0	$ 129,405	$ 14,323

Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ (49,439)	$ (42,556)	$ 21,153	$ (107,373)
Other comprehensive income (loss):
Foreign currency translation adjustments	623	72	734	503
Available-for-sale investments:
Unrealized gain on investments, net of tax effect	(385)	(31)	712	(28)
Other comprehensive income, net of taxes	238	41	1,446	475
Comprehensive income (loss)	$ (49,201)	$ (42,515)	$ 22,599	$ (106,898)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Condensed Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]	Noncontrolling Interests [Member]
Balance at Dec. 31, 2017	$ 547,738	$ 825	$ 1,160,094	$ (1,795)	$ (630,657)	$ 19,271
Balance, Shares at Dec. 31, 2017		82,498,128
Impact of change in accounting principle upon adoption \| ASU 2016-01 [Member]	0	$ 0	0	(1,250)	1,250	0
Net income (loss)	(107,373)	0	0	0	(107,373)	0
Change in unrealized gain or loss on investments	(28)	0	0	(28)	0	0
Foreign currency translation adjustments	503	0	0	503	0	0
Shares issued from stock plans, net of payroll taxes paid	11,310	$ 23	11,287	0	0	0
Shares issued from stock plans, net of payroll taxes paid, Shares		2,348,614
Stock-based compensation	38,432	$ 0	38,432	0	0	0
Balance at Sep. 30, 2018	490,582	$ 848	1,209,813	(2,570)	(736,780)	19,271
Balance, Shares at Sep. 30, 2018		84,846,742
Balance at Jun. 30, 2018	514,802	$ 842	1,191,524	(2,611)	(694,224)	19,271
Balance, Shares at Jun. 30, 2018		84,182,844
Net income (loss)	(42,556)	$ 0	0	0	(42,556)	0
Change in unrealized gain or loss on investments	(31)	0	0	(31)	0	0
Foreign currency translation adjustments	72	0	0	72	0	0
Shares issued from stock plans, net of payroll taxes paid	3,972	$ 6	3,966	0	0	0
Shares issued from stock plans, net of payroll taxes paid, Shares		663,898
Stock-based compensation	14,323	$ 0	14,323	0	0	0
Balance at Sep. 30, 2018	490,582	$ 848	1,209,813	(2,570)	(736,780)	19,271
Balance, Shares at Sep. 30, 2018		84,846,742
Balance at Dec. 31, 2018	528,470	$ 854	1,226,453	(2,281)	(715,827)	19,271
Balance, Shares at Dec. 31, 2018		85,432,102
Impact of change in accounting principle upon adoption \| ASU 2016-02 [Member]	8,688	$ 0	0	0	8,688	0
Impact of change in accounting principle upon adoption \| ASU 2018-02 [Member]	0	0	0	611	(611)	0
Net income (loss)	21,153	0	0	0	21,153	0
Change in unrealized gain or loss on investments	712	0	0	712	0	0
Foreign currency translation adjustments	734	0	0	734	0	0
Shares issued from stock plans, net of payroll taxes paid	5,096	$ 18	5,078	0	0	0
Shares issued from stock plans, net of payroll taxes paid, Shares		1,778,567
Stock-based compensation	48,865	$ 0	48,865	0	0	0
Balance at Sep. 30, 2019	613,718	$ 872	1,280,396	(224)	(686,597)	19,271
Balance, Shares at Sep. 30, 2019		87,210,669
Balance at Jun. 30, 2019	648,302	$ 868	1,265,783	(462)	(637,158)	19,271
Balance, Shares at Jun. 30, 2019		86,847,072
Net income (loss)	(49,439)	$ 0	0	0	(49,439)	0
Change in unrealized gain or loss on investments	(385)	0	0	(385)	0	0
Foreign currency translation adjustments	623	0	0	623	0	0
Shares issued from stock plans, net of payroll taxes paid	(176)	$ 4	(180)	0	0	0
Shares issued from stock plans, net of payroll taxes paid, Shares		363,597
Stock-based compensation	14,793	$ 0	14,793	0	0	0
Balance at Sep. 30, 2019	$ 613,718	$ 872	$ 1,280,396	$ (224)	$ (686,597)	$ 19,271
Balance, Shares at Sep. 30, 2019		87,210,669

Condensed Consolidated Statement of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Operating activities
Net income (loss)	$ 21,153	$ (107,373)
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Depreciation	8,715	4,693
Amortization of finance lease right-of-use assets	7,720	0
Net amortization of premium and discount on investments	(3,354)	584
Unrealized loss (gain) on cash equivalents and short-term equity investments	(78)	1,103
Loss (gain) on disposal of property and equipment	(10)	53
Stock-based compensation	48,865	38,432
Realized foreign currency gain	0	(1,074)
Realized gain on sales of available-for-sale securities	0	(87)
Changes in operating assets and liabilities:
Accounts receivable	44,459	(14,735)
Inventories	(4,908)	0
Prepaid expenses and other current assets	(128,922)	1,935
Other assets	(953)	1,350
Accounts payable	(5,084)	4,622
Accrued and other liabilities	5,484	(9,885)
Deferred revenue	(50,915)	19,660
Lease obligations	0	35
Accrued interest for finance lease liabilities	104	0
Other long-term liabilities	24,069	2,008
Net cash used in operating activities	(33,655)	(58,679)
Investing activities
Purchases of property and equipment	(4,017)	(4,852)
Proceeds from sale of property and equipment	0	184
Purchases of available-for-sale securities and term deposit	(155,932)	(110,156)
Proceeds from sales of available-for-sale securities	0	8,167
Proceeds from maturities of investments	305,000	47,390
Net cash provided by (used in) investing activities	145,051	(59,267)
Financing activities
Borrowings under capital lease obligations	0	49
Repayments of finance lease liabilities	(8,810)	0
Repayments of lease obligations	(302)	(302)
Cash paid for payroll taxes on restricted stock unit releases	(10,614)	(13,288)
Proceeds from issuance of common stock	15,710	24,598
Net cash provided by (used in) financing activities	(4,016)	11,057
Effect of exchange rate change on cash and cash equivalents	(46)	(47)
Net increase (decrease) in cash and cash equivalents	107,334	(106,936)
Total cash and cash equivalents at beginning of period	89,258	673,658
Total cash and cash equivalents at end of period	$ 196,592	$ 566,722

Significant Accounting Policies

9 Months Ended

Sep. 30, 2019

Accounting Policies [Abstract]

Significant Accounting Policies

1.	Significant Accounting Policies

Description of Operations

Basis of Presentation and Principles of Consolidation

Leases

Inventories

Net product sales

Use of Estimates

Net Income (Loss) per Share

The following is a reconciliation of the basic and diluted net income (loss) per share calculation for the periods presented (in thousands, except per share data):

	Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019		2018
Net income (loss)	$	(49,439	)	$	(42,556	)	$	21,153	$	(107,373	)
Weighted average shares used to compute net income (loss) per share:
Basic		87,007			84,508			86,390		83,713
Dilutive effect of potential common shares		—			—			5,605		—
Diluted		87,007			84,508			91,995		83,713

Net income (loss) per share:
Basic	$	(0.57	)	$	(0.50	)	$	0.24	$	(1.28	)
Diluted	$	(0.57	)	$	(0.50	)	$	0.23	$	(1.28	)

Recently Issued and Adopted Accounting Guidance

ASC 842

The impacts to the select line items from the Company’s condensed consolidated balance sheet upon adoption of the ASC 842 guidance are as follows (in thousands):

Balance Sheet Line Item	Nature of Adjustment	New Lease Guidance Adoption Adjustment
Assets
Property and equipment, net	Derecognition - build-to-suit lease assets - building shell, cost	$	(53,880	)
	Derecognition - build-to-suit lease assets - building shell, accumulated depreciation		13,476
	Change of useful life - leasehold improvements, accumulated depreciation		(38,877	)
Finance lease right-of-use assets	Recognition - finance lease ROU assets		49,597
Other assets	Recognition - operating lease ROU assets		730
Liabilities
Accrued and other current liabilities	Derecognition - deferred rent, current		(619	)
	Derecognition - build-to-suit lease liabilities, current		(545	)
	Recognition - operating lease liabilities, current		404
Finance lease liabilities, current	Recognition - finance lease liabilities, current		11,499
Long-term portion of lease obligations	Derecognition - build-to-suit lease liabilities, non-current		(95,613	)
Deferred rent	Derecognition - deferred rent, non-current		(3,038	)
Finance lease liabilities, non-current	Recognition - finance lease liabilities, non-current		49,884
Other long-term liabilities	Recognition - operating lease liabilities, non-current		250
Stockholders’ equity
Accumulated deficit	Cumulative decrease to accumulated deficit	$	8,688

ASU 2018-02

	Accumulated Other Comprehensive Loss			Accumulated Deficit
Balance at December 31, 2018	$	(2,281	)	$	(715,827	)
Impact of change in accounting principle upon adoption of ASU 2018-02		611			(611	)
Opening balance as of January 1, 2019	$	(1,670	)	$	(716,438	)

SEC Disclosure Requirement

ASU 2018-07

Recently Issued Accounting Guidance Not Yet Adopted

Collaboration Agreements

9 Months Ended

Sep. 30, 2019

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Collaboration Agreements

2.	Collaboration Agreements

Astellas Agreements

Japan Agreement

Europe Agreement

AstraZeneca Agreements

U.S./Rest of World (“RoW”) Agreement

China Agreement

Summary of Revenue Recognized Under the Collaboration Agreements

Amounts recognized as revenue under the Japan Agreement were as follows (in thousands):

		Three Months Ended September 30,				Nine Months Ended September 30,
Agreement	Performance Obligation	2019		2018		2019		2018
Japan	License revenue	$	11,935	$	—	$	11,935	$	14,323
	Development revenue	$	537	$	474	$	1,151	$	2,065

Japan Agreement	Cumulative Revenue Through September 30, 2019		Deferred Revenue at September 30, 2019		Total Consideration Through September 30, 2019
License	$	86,024	$	—	$	86,024
Development revenue		15,060		312		15,372
Total license and development revenue	$	101,084	$	312	$	101,396

Amounts recognized as revenue under the Europe Agreement were as follows (in thousands):

		Three Months Ended September 30,				Nine Months Ended September 30,
Agreement	Performance Obligation	2019		2018		2019		2018
Europe	License revenue	$	—	$	—	$	117,470	$	—
	Development revenue	$	2,996	$	4,658	$	24,463	$	14,384

Europe Agreement	Cumulative Revenue Through September 30, 2019		Deferred Revenue at September 30, 2019			Total Consideration Through September 30, 2019
License	$	487,951	$	—		$	487,951
Development revenue		227,300		3,988			231,288
Total license and development revenue	$	715,251	$	3,988	*	$	719,239

_______________________________________________________________________________________________________

Amounts recognized as revenue under the U.S./RoW Agreement were as follows (in thousands):

		Three Months Ended September 30,				Nine Months Ended September 30,
Agreement	Performance Obligation	2019		2018		2019		2018
U.S. / RoW and China	License revenue	$	—	$	—	$	33,112	$	—
	Development revenue		17,106		23,895		59,872		74,096
	China performance obligation	$	19	$	—	$	19	$	—

U.S. / RoW and China Agreements	Cumulative Revenue Through September 30, 2019		Deferred Revenue at September 30, 2019			Total Consideration Through September 30, 2019
License	$	327,275	$	—		$	327,275
Co-development, information sharing & committee services		468,509		11,317			479,826
China performance obligation		19		137,330			137,349
Total license and development revenue	$	795,803	$	148,647	*	$	944,450

_______________________________________________________________________________________________________

Product Revenue

Other Revenues

Other revenues consist primarily of collagen material sold for research purposes. Other revenues were immaterial for all periods presented.

Deferred Revenue

Fair Value Measurements

9 Months Ended

Sep. 30, 2019

Fair Value Disclosures [Abstract]

Fair Value Measurements

3.	Fair Value Measurements

The fair values of the Company’s financial assets that are measured on a recurring basis are as follows (in thousands):

	September 30, 2019
	Level 1		Level 2		Level 3		Total
US treasury notes and bills	$	226,590	$	175,450	$	—	$	402,040
Bond and mutual funds		10,748		—		—		10,748
Equity investments		251		—		—		251
Money market funds		105,822		—		—		105,822
Certificate of deposit		—		30,000		—		30,000
Total	$	343,411	$	205,450	$	—	$	548,861

	December 31, 2018
	Level 1		Level 2		Level 3		Total
US treasury notes and bills	$	292,317	$	224,953	$	—	$	517,270
Bond and mutual funds		10,484		—		—		10,484
Equity investments		234		—		—		234
Money market funds		541		—		—		541
Term deposit		—		80,000		—		80,000
Certificate of deposit		—		29,910		—		29,910
Total	$	303,576	$	334,863	$	—	$	638,439

The fair values of the Company’s financial liabilities that are carried at historical cost are as follows (in thousands):

	September 30, 2019
	Level 1		Level 2		Level 3		Total
Lease obligations	$	—	$	—	$	1,645	$	1,645

	December 31, 2018
	Level 1		Level 2		Level 3		Total
Lease obligations	$	—	$	—	$	98,105	$	98,105

The fair values of the Company’s financial liabilities were derived by using an income approach, which required Level 3 inputs such as discounted estimated future cash flows.

There were no transfers of assets or liabilities between levels for any of the periods presented.

- Definition

+ References + Details

Leases

9 Months Ended

Sep. 30, 2019

Leases [Abstract]

Leases

The Company currently has two building leases treated as finance leases.

The Company’s lease assets and related lease liabilities were as follows (in thousands):

	Balance Sheet Line Item	September 30, 2019
Assets
Finance:
Right-of-use assets - cost		$	49,784
Accumulated amortization			(7,720	)
Finance lease right-of-use assets, net	Finance lease right-of-use assets		42,064
Operating:
Right-of-use assets - cost			2,723
Accumulated amortization			(531	)
Operating lease right-of-use assets, net	Other assets		2,192
Total lease assets		$	44,256

Liabilities
Current:
Finance lease liabilities	Finance lease liabilities, current	$	12,149
Operating lease liabilities	Accrued and other current liabilities		998
Non-current:
Finance lease liabilities	Finance lease liabilities, non-current		40,713
Operating lease liabilities	Other long-term liabilities		1,133
Total lease liabilities		$	54,993

The components of lease expense were as follows (in thousands):

	Statement of Operations Line Item	Three Months Ended September 30, 2019			Nine Months Ended September 30, 2019
Finance lease cost:
Amortization of right-of-use assets	Selling, general and administrative expenses	$	2,580		$	7,720
Interest on lease liabilities	Interest expense		578			1,826
Operating lease cost	Research and development, Selling, general and administrative expenses		290			579
Sublease income	Selling, general and administrative expenses		(310	)		(1,135	)
Total lease cost		$	3,138		$	8,990

Supplemental cash flow information related to leases were as follows (in thousands):

	Nine Months Ended September 30, 2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$	540
Operating cash flows from finance leases		1,640
Financing cash flows from finance leases		8,810
Right-of-use assets obtained in exchange for new lease liabilities:
Finance leases		49,784
Operating leases	$	2,723

Lease term and discount rate were as follows at September 30, 2019:

	September 30, 2019
Weighted-average remaining lease term (years):
Finance leases		3.8
Operating leases		2.3
Weighted-average discount rate:
Finance leases		4.43	%
Operating leases		4.75	%

Maturities of lease liabilities are as follows:

Year Ending	Finance Leases			Operating Leases
2019 (Remaining three month period)	$	3,466		$	280
2020		14,060			1,013
2021		13,675			651
2022		13,878			300
2023		12,523			—
Total future lease payments		57,602			2,244
Less: Interest		(4,740	)		(113	)
Present value of lease liabilities	$	52,862		$	2,131

The following information was previously disclosed under ASC 840 as of December 31, 2018:

Future minimum lease payments under all non-cancelable operating lease obligations as of December 31, 2018 were as follows (in thousands):

Year Ending	Operating Leases
2019	$	444
2020		232
2021		25
2022		16
2023		—
Total minimum payments	$	717

Future minimum lease payments, on a consolidated basis, under the Company’s facility lease financing obligations as of December 31, 2018 were as follows (in thousands):

Year Ending	Lease financing obligations
2019	$	14,379
2020		14,664
2021		14,179
2022		14,335
2023		12,872
Total minimum payments	$	70,429

Balance Sheet Components

9 Months Ended

Sep. 30, 2019

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Balance Sheet Components

5.	Balance Sheet Components

Cash and Cash Equivalents

Cash and cash equivalents consisted of the following (in thousands):

	September 30, 2019		December 31, 2018
Cash	$	90,770	$	38,783
US treasury notes and bills		—		49,934
Money market funds		105,822		541
Total cash and cash equivalents	$	196,592	$	89,258

Investments

	September 30, 2019
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Fair Value
US treasury notes and bills	$	401,377	$	688	$	(25	)	$	402,040
Certificates of deposit		30,000		—		—			30,000
Bond and mutual funds		10,668		80		—			10,748
Equity investments		125		126		—			251
Total investments	$	442,170	$	894	$	(25	)	$	443,039

	December 31, 2018
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Fair Value
US treasury notes and bills	$	467,296	$	109	$	(69	)	$	467,336
Term deposit		80,000		—		—			80,000
Certificates of deposit		30,000		—		(90	)		29,910
Bond and mutual funds		10,464		20		—			10,484
Equity investments		125		109		—			234
Total investments	$	587,885	$	238	$	(159	)	$	587,964

Inventories

Inventories consisted of the following (in thousands):

	September 30, 2019
Raw materials	$	658
Work-in-progress		1,155
Finished goods		3,095
Total inventories	$	4,908

Prepaid expenses and other current assets

Prepaid expenses and other current assets consisted of the following (in thousands):

	September 30, 2019			December 31, 2018
Unbilled contract assets	$	180,000		$	—
Deferred revenues from associated contracts		(53,988	)		—
Net unbilled contract assets		126,012			—
Prepaid assets		4,051			2,705
Other current assets		3,652			2,224
Total prepaid expenses and other current assets	$	133,715		$	4,929

Property and Equipment

Property and equipment consisted of the following (in thousands):

	September 30, 2019			December 31, 2018
Leasehold improvements	$	101,339		$	101,200
Building shell		—			53,880
Laboratory equipment		16,932			16,405
Machinery		8,691			8,382
Computer equipment		7,227			6,473
Furniture and fixtures		5,789			5,690
Construction in progress		2,332			367
Total property and equipment	$	142,310		$	192,397
Less: accumulated depreciation		(99,102	)		(65,199	)
Property and equipment, net	$	43,208		$	127,198

Accrued Liabilities

Accrued liabilities consisted of the following (in thousands):

	September 30, 2019		December 31, 2018
Preclinical and clinical trial accruals	$	41,546	$	35,413
Payroll and related accruals		17,604		21,430
Property taxes and other		2,389		1,095
Professional services		4,063		2,648
Other		5,223		5,537
Total accrued liabilities	$	70,825	$	66,123

Stock-Based Compensation

9 Months Ended

Sep. 30, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

6.	Stock-Based Compensation

Stock-based compensation expense was allocated to research and development and selling, general and administrative expense as follows (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
Research and development	$	10,185	$	8,465	$	30,214	$	22,729
Selling, general and administrative		4,608		5,858		18,651		15,703
Total stock-based compensation expense	$	14,793	$	14,323	$	48,865	$	38,432

	Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019			2018
Stock Options
Expected term (in years)		5.3			5.3			5.3			5.4
Expected volatility		67.8	%		68.1	%		67.9	%		67.8	%
Risk-free interest rate		1.7	%		2.9	%		2.4	%		2.7	%
Expected dividend yield		—			—			—			—
Weighted average estimated fair value	$	25.17		$	35.99		$	32.44		$	32.37

ESPPs
Expected term (in years)	0.5 - 2.0			0.5 - 2.0			0.5 - 2.0			0.5 - 2.0
Expected volatility	48.1 - 62.1		%	47.3 - 72.8		%	48.1 - 62.1		%	47.3 - 75.3		%
Risk-free interest rate	1.6 - 2.9		%	1.0 - 2.6		%	1.3 - 2.9		%	0.8 - 2.6		%
Expected dividend yield		—			—			—			—
Weighted average estimated fair value	$	19.27		$	20.10		$	19.53		$	15.27

Income Taxes

9 Months Ended

Sep. 30, 2019

Income Tax Disclosure [Abstract]

Income Taxes

7.	Income Taxes

The provisions for income taxes for the three and nine months ended September 30, 2019 and 2018 were due to foreign taxes.

Related Party Transactions

9 Months Ended

Sep. 30, 2019

Related Party Transactions

8.	Related Party Transactions

Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2019

Accounting Policies [Abstract]

Description of Operations

Basis of Presentation and Principles of Consolidation

Net product sales

Net Income (Loss) per Share

The following is a reconciliation of the basic and diluted net income (loss) per share calculation for the periods presented (in thousands, except per share data):

	Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019		2018
Net income (loss)	$	(49,439	)	$	(42,556	)	$	21,153	$	(107,373	)
Weighted average shares used to compute net income (loss) per share:
Basic		87,007			84,508			86,390		83,713
Dilutive effect of potential common shares		—			—			5,605		—
Diluted		87,007			84,508			91,995		83,713

Net income (loss) per share:
Basic	$	(0.57	)	$	(0.50	)	$	0.24	$	(1.28	)
Diluted	$	(0.57	)	$	(0.50	)	$	0.23	$	(1.28	)

Recently Issued and Adopted Accounting Guidance

ASC 842

The impacts to the select line items from the Company’s condensed consolidated balance sheet upon adoption of the ASC 842 guidance are as follows (in thousands):

Balance Sheet Line Item	Nature of Adjustment	New Lease Guidance Adoption Adjustment
Assets
Property and equipment, net	Derecognition - build-to-suit lease assets - building shell, cost	$	(53,880	)
	Derecognition - build-to-suit lease assets - building shell, accumulated depreciation		13,476
	Change of useful life - leasehold improvements, accumulated depreciation		(38,877	)
Finance lease right-of-use assets	Recognition - finance lease ROU assets		49,597
Other assets	Recognition - operating lease ROU assets		730
Liabilities
Accrued and other current liabilities	Derecognition - deferred rent, current		(619	)
	Derecognition - build-to-suit lease liabilities, current		(545	)
	Recognition - operating lease liabilities, current		404
Finance lease liabilities, current	Recognition - finance lease liabilities, current		11,499
Long-term portion of lease obligations	Derecognition - build-to-suit lease liabilities, non-current		(95,613	)
Deferred rent	Derecognition - deferred rent, non-current		(3,038	)
Finance lease liabilities, non-current	Recognition - finance lease liabilities, non-current		49,884
Other long-term liabilities	Recognition - operating lease liabilities, non-current		250
Stockholders’ equity
Accumulated deficit	Cumulative decrease to accumulated deficit	$	8,688

ASU 2018-02

	Accumulated Other Comprehensive Loss			Accumulated Deficit
Balance at December 31, 2018	$	(2,281	)	$	(715,827	)
Impact of change in accounting principle upon adoption of ASU 2018-02		611			(611	)
Opening balance as of January 1, 2019	$	(1,670	)	$	(716,438	)

SEC Disclosure Requirement

ASU 2018-07

Recently Issued Accounting Guidance Not Yet Adopted

Collaboration Arrangements

Astellas Agreements

Japan Agreement

Europe Agreement

AstraZeneca Agreements

U.S./Rest of World (“RoW”) Agreement

China Agreement

Other Revenues

Product Revenue

Other Revenues

Other revenues consist primarily of collagen material sold for research purposes. Other revenues were immaterial for all periods presented.

Product Revenue

Deferred Revenue

Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2019

Summary of Reconciliation of Basic and Diluted Net Income (Loss) Per Share Calculation

The following is a reconciliation of the basic and diluted net income (loss) per share calculation for the periods presented (in thousands, except per share data):

	Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019		2018
Net income (loss)	$	(49,439	)	$	(42,556	)	$	21,153	$	(107,373	)
Weighted average shares used to compute net income (loss) per share:
Basic		87,007			84,508			86,390		83,713
Dilutive effect of potential common shares		—			—			5,605		—
Diluted		87,007			84,508			91,995		83,713

Net income (loss) per share:
Basic	$	(0.57	)	$	(0.50	)	$	0.24	$	(1.28	)
Diluted	$	(0.57	)	$	(0.50	)	$	0.23	$	(1.28	)

ASU 2016-02 [Member]

Schedule of Impacts Upon Adoption of New Guidance

The impacts to the select line items from the Company’s condensed consolidated balance sheet upon adoption of the ASC 842 guidance are as follows (in thousands):

Balance Sheet Line Item	Nature of Adjustment	New Lease Guidance Adoption Adjustment
Assets
Property and equipment, net	Derecognition - build-to-suit lease assets - building shell, cost	$	(53,880	)
	Derecognition - build-to-suit lease assets - building shell, accumulated depreciation		13,476
	Change of useful life - leasehold improvements, accumulated depreciation		(38,877	)
Finance lease right-of-use assets	Recognition - finance lease ROU assets		49,597
Other assets	Recognition - operating lease ROU assets		730
Liabilities
Accrued and other current liabilities	Derecognition - deferred rent, current		(619	)
	Derecognition - build-to-suit lease liabilities, current		(545	)
	Recognition - operating lease liabilities, current		404
Finance lease liabilities, current	Recognition - finance lease liabilities, current		11,499
Long-term portion of lease obligations	Derecognition - build-to-suit lease liabilities, non-current		(95,613	)
Deferred rent	Derecognition - deferred rent, non-current		(3,038	)
Finance lease liabilities, non-current	Recognition - finance lease liabilities, non-current		49,884
Other long-term liabilities	Recognition - operating lease liabilities, non-current		250
Stockholders’ equity
Accumulated deficit	Cumulative decrease to accumulated deficit	$	8,688

ASU 2018-02 [Member]

Schedule of Impacts Upon Adoption of New Guidance

The impacts, based on the aggregate portfolio approach, to the Company’s accumulated other comprehensive loss and accumulated deficit upon adoption of this guidance are as follows (in thousands):

	Accumulated Other Comprehensive Loss			Accumulated Deficit
Balance at December 31, 2018	$	(2,281	)	$	(715,827	)
Impact of change in accounting principle upon adoption of ASU 2018-02		611			(611	)
Opening balance as of January 1, 2019	$	(1,670	)	$	(716,438	)

Collaboration Agreements (Tables)

9 Months Ended

Sep. 30, 2019

Japan [Member]

Summary of Revenue Recognized under Agreement

Amounts recognized as revenue under the Japan Agreement were as follows (in thousands):

		Three Months Ended September 30,				Nine Months Ended September 30,
Agreement	Performance Obligation	2019		2018		2019		2018
Japan	License revenue	$	11,935	$	—	$	11,935	$	14,323
	Development revenue	$	537	$	474	$	1,151	$	2,065

Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations along with Associated Deferred Revenue

Japan Agreement	Cumulative Revenue Through September 30, 2019		Deferred Revenue at September 30, 2019		Total Consideration Through September 30, 2019
License	$	86,024	$	—	$	86,024
Development revenue		15,060		312		15,372
Total license and development revenue	$	101,084	$	312	$	101,396

Europe [Member]

Summary of Revenue Recognized under Agreement

Amounts recognized as revenue under the Europe Agreement were as follows (in thousands):

		Three Months Ended September 30,				Nine Months Ended September 30,
Agreement	Performance Obligation	2019		2018		2019		2018
Europe	License revenue	$	—	$	—	$	117,470	$	—
	Development revenue	$	2,996	$	4,658	$	24,463	$	14,384

Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations along with Associated Deferred Revenue

Europe Agreement	Cumulative Revenue Through September 30, 2019		Deferred Revenue at September 30, 2019			Total Consideration Through September 30, 2019
License	$	487,951	$	—		$	487,951
Development revenue		227,300		3,988			231,288
Total license and development revenue	$	715,251	$	3,988	*	$	719,239

_______________________________________________________________________________________________________

U.S./RoW and China [Member]

Summary of Revenue Recognized under Agreement

Amounts recognized as revenue under the U.S./RoW Agreement were as follows (in thousands):

		Three Months Ended September 30,				Nine Months Ended September 30,
Agreement	Performance Obligation	2019		2018		2019		2018
U.S. / RoW and China	License revenue	$	—	$	—	$	33,112	$	—
	Development revenue		17,106		23,895		59,872		74,096
	China performance obligation	$	19	$	—	$	19	$	—

Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations along with Associated Deferred Revenue

U.S. / RoW and China Agreements	Cumulative Revenue Through September 30, 2019		Deferred Revenue at September 30, 2019			Total Consideration Through September 30, 2019
License	$	327,275	$	—		$	327,275
Co-development, information sharing & committee services		468,509		11,317			479,826
China performance obligation		19		137,330			137,349
Total license and development revenue	$	795,803	$	148,647	*	$	944,450

_______________________________________________________________________________________________________

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2019

Fair Value Disclosures [Abstract]

Fair Values of Financial Assets Measured on Recurring Basis

The fair values of the Company’s financial assets that are measured on a recurring basis are as follows (in thousands):

	September 30, 2019
	Level 1		Level 2		Level 3		Total
US treasury notes and bills	$	226,590	$	175,450	$	—	$	402,040
Bond and mutual funds		10,748		—		—		10,748
Equity investments		251		—		—		251
Money market funds		105,822		—		—		105,822
Certificate of deposit		—		30,000		—		30,000
Total	$	343,411	$	205,450	$	—	$	548,861

	December 31, 2018
	Level 1		Level 2		Level 3		Total
US treasury notes and bills	$	292,317	$	224,953	$	—	$	517,270
Bond and mutual funds		10,484		—		—		10,484
Equity investments		234		—		—		234
Money market funds		541		—		—		541
Term deposit		—		80,000		—		80,000
Certificate of deposit		—		29,910		—		29,910
Total	$	303,576	$	334,863	$	—	$	638,439

Fair Values of Financial Liabilities Carried at Historical Cost

The fair values of the Company’s financial liabilities that are carried at historical cost are as follows (in thousands):

	September 30, 2019
	Level 1		Level 2		Level 3		Total
Lease obligations	$	—	$	—	$	1,645	$	1,645

	December 31, 2018
	Level 1		Level 2		Level 3		Total
Lease obligations	$	—	$	—	$	98,105	$	98,105

Leases (Tables)

9 Months Ended

Sep. 30, 2019

Leases [Abstract]

Schedule of Lease Assets and Related Lease Liabilities

The Company’s lease assets and related lease liabilities were as follows (in thousands):

	Balance Sheet Line Item	September 30, 2019
Assets
Finance:
Right-of-use assets - cost		$	49,784
Accumulated amortization			(7,720	)
Finance lease right-of-use assets, net	Finance lease right-of-use assets		42,064
Operating:
Right-of-use assets - cost			2,723
Accumulated amortization			(531	)
Operating lease right-of-use assets, net	Other assets		2,192
Total lease assets		$	44,256

Liabilities
Current:
Finance lease liabilities	Finance lease liabilities, current	$	12,149
Operating lease liabilities	Accrued and other current liabilities		998
Non-current:
Finance lease liabilities	Finance lease liabilities, non-current		40,713
Operating lease liabilities	Other long-term liabilities		1,133
Total lease liabilities		$	54,993

Components of Lease Expense

The components of lease expense were as follows (in thousands):

	Statement of Operations Line Item	Three Months Ended September 30, 2019			Nine Months Ended September 30, 2019
Finance lease cost:
Amortization of right-of-use assets	Selling, general and administrative expenses	$	2,580		$	7,720
Interest on lease liabilities	Interest expense		578			1,826
Operating lease cost	Research and development, Selling, general and administrative expenses		290			579
Sublease income	Selling, general and administrative expenses		(310	)		(1,135	)
Total lease cost		$	3,138		$	8,990

Schedule of Supplemental Cash Flow Information Related to Leases

Supplemental cash flow information related to leases were as follows (in thousands):

	Nine Months Ended September 30, 2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$	540
Operating cash flows from finance leases		1,640
Financing cash flows from finance leases		8,810
Right-of-use assets obtained in exchange for new lease liabilities:
Finance leases		49,784
Operating leases	$	2,723

Schedule of Lease Term and Discount Rate

Lease term and discount rate were as follows at September 30, 2019:

	September 30, 2019
Weighted-average remaining lease term (years):
Finance leases		3.8
Operating leases		2.3
Weighted-average discount rate:
Finance leases		4.43	%
Operating leases		4.75	%

Schedule of Maturities of Finance and Operating Leases Liabilities

Maturities of lease liabilities are as follows:

Year Ending	Finance Leases			Operating Leases
2019 (Remaining three month period)	$	3,466		$	280
2020		14,060			1,013
2021		13,675			651
2022		13,878			300
2023		12,523			—
Total future lease payments		57,602			2,244
Less: Interest		(4,740	)		(113	)
Present value of lease liabilities	$	52,862		$	2,131

Schedule of Future Minimum Lease Payments Under all Non-Cancelable Operating Lease Obligations

Future minimum lease payments under all non-cancelable operating lease obligations as of December 31, 2018 were as follows (in thousands):

Year Ending	Operating Leases
2019	$	444
2020		232
2021		25
2022		16
2023		—
Total minimum payments	$	717

Schedule of Future Minimum Lease Payments on Consolidated Basis Under Company's Facility Financing Lease Obligations

Future minimum lease payments, on a consolidated basis, under the Company’s facility lease financing obligations as of December 31, 2018 were as follows (in thousands):

Year Ending	Lease financing obligations
2019	$	14,379
2020		14,664
2021		14,179
2022		14,335
2023		12,872
Total minimum payments	$	70,429

Balance Sheet Components (Tables)

9 Months Ended

Sep. 30, 2019

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Schedule of Cash and Cash Equivalents

Cash and cash equivalents consisted of the following (in thousands):

	September 30, 2019		December 31, 2018
Cash	$	90,770	$	38,783
US treasury notes and bills		—		49,934
Money market funds		105,822		541
Total cash and cash equivalents	$	196,592	$	89,258

Summary of Amortized Cost, Gross Unrealized Holding Gains or Losses, and Fair Value of Available-for-Sale Investments

	September 30, 2019
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Fair Value
US treasury notes and bills	$	401,377	$	688	$	(25	)	$	402,040
Certificates of deposit		30,000		—		—			30,000
Bond and mutual funds		10,668		80		—			10,748
Equity investments		125		126		—			251
Total investments	$	442,170	$	894	$	(25	)	$	443,039

	December 31, 2018
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Fair Value
US treasury notes and bills	$	467,296	$	109	$	(69	)	$	467,336
Term deposit		80,000		—		—			80,000
Certificates of deposit		30,000		—		(90	)		29,910
Bond and mutual funds		10,464		20		—			10,484
Equity investments		125		109		—			234
Total investments	$	587,885	$	238	$	(159	)	$	587,964

Schedule of Inventory

Inventories consisted of the following (in thousands):

	September 30, 2019
Raw materials	$	658
Work-in-progress		1,155
Finished goods		3,095
Total inventories	$	4,908

Schedule of Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consisted of the following (in thousands):

	September 30, 2019			December 31, 2018
Unbilled contract assets	$	180,000		$	—
Deferred revenues from associated contracts		(53,988	)		—
Net unbilled contract assets		126,012			—
Prepaid assets		4,051			2,705
Other current assets		3,652			2,224
Total prepaid expenses and other current assets	$	133,715		$	4,929

Schedule of Property and Equipment

Property and equipment consisted of the following (in thousands):

	September 30, 2019			December 31, 2018
Leasehold improvements	$	101,339		$	101,200
Building shell		—			53,880
Laboratory equipment		16,932			16,405
Machinery		8,691			8,382
Computer equipment		7,227			6,473
Furniture and fixtures		5,789			5,690
Construction in progress		2,332			367
Total property and equipment	$	142,310		$	192,397
Less: accumulated depreciation		(99,102	)		(65,199	)
Property and equipment, net	$	43,208		$	127,198

Schedule of Accrued Liabilities

Accrued liabilities consisted of the following (in thousands):

	September 30, 2019		December 31, 2018
Preclinical and clinical trial accruals	$	41,546	$	35,413
Payroll and related accruals		17,604		21,430
Property taxes and other		2,389		1,095
Professional services		4,063		2,648
Other		5,223		5,537
Total accrued liabilities	$	70,825	$	66,123

Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Allocated Stock-Based Compensation Expense

Stock-based compensation expense was allocated to research and development and selling, general and administrative expense as follows (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
Research and development	$	10,185	$	8,465	$	30,214	$	22,729
Selling, general and administrative		4,608		5,858		18,651		15,703
Total stock-based compensation expense	$	14,793	$	14,323	$	48,865	$	38,432

Schedule of Assumptions used to Estimate Fair Value of Stock Options Granted and Purchases under 2014 Employee Share Purchase Plan

	Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019			2018
Stock Options
Expected term (in years)		5.3			5.3			5.3			5.4
Expected volatility		67.8	%		68.1	%		67.9	%		67.8	%
Risk-free interest rate		1.7	%		2.9	%		2.4	%		2.7	%
Expected dividend yield		—			—			—			—
Weighted average estimated fair value	$	25.17		$	35.99		$	32.44		$	32.37

ESPPs
Expected term (in years)	0.5 - 2.0			0.5 - 2.0			0.5 - 2.0			0.5 - 2.0
Expected volatility	48.1 - 62.1		%	47.3 - 72.8		%	48.1 - 62.1		%	47.3 - 75.3		%
Risk-free interest rate	1.6 - 2.9		%	1.0 - 2.6		%	1.3 - 2.9		%	0.8 - 2.6		%
Expected dividend yield		—			—			—			—
Weighted average estimated fair value	$	19.27		$	20.10		$	19.53		$	15.27

Significant Accounting Policies - Additional Information (Detail) shares in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019 shares	Sep. 30, 2018 shares	Sep. 30, 2019 Segment shares	Sep. 30, 2018 shares	Dec. 31, 2017
Accounting Policies [Abstract]
Number of operating segment \| Segment			1
Short term investments maturity			12 months
Anti-dilutive shares \| shares	9.2	9.3	3.6	9.1
U.S. federal statutory income tax rate			21.00%		35.00%

Significant Accounting Policies - Summary of Reconciliation of Basic and Diluted Net Income (Loss) Per Share Calculation (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share [Abstract]
Net income (loss)	$ (49,439)	$ (42,556)	$ 21,153	$ (107,373)
Weighted average number of common shares used to calculate net income (loss) per share:
Basic	87,007	84,508	86,390	83,713
Dilutive effect of potential common shares	0	0	5,605	0
Diluted	87,007	84,508	91,995	83,713
Net income (loss) per share:
Basic	$ (0.57)	$ (0.50)	$ 0.24	$ (1.28)
Diluted	$ (0.57)	$ (0.50)	$ 0.23	$ (1.28)

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Summary of Significant Accounting Policies - Schedule of Impacts to Condensed Consolidated Balance Sheet Upon Adoption of 842 Guidance (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Assets
Property and equipment, net	$ 43,208	$ 127,198
Finance lease right-of-use assets	42,064	0
Liabilities, stockholders’ equity and non-controlling interests
Finance lease liabilities, current	12,149	0
Deferred rent	0	3,038
Finance lease liabilities, non-current	40,713	0
Accumulated deficit	(686,597)	$ (715,827)
Derecognition Build to Suit Lease Assets [Member] \| Building Shell [Member]
Assets
Property and equipment, net	(53,880)
Derecognition Build to Suit Lease Assets Accumulated Depreciation [Member] \| Building Shell [Member]
Assets
Property and equipment, net	13,476
Leasehold Improvements Accumulated Depreciation [Member]
Assets
Property and equipment, net	(38,877)
Recognition Finance Lease Assets [Member]
Assets
Finance lease right-of-use assets	49,597
Recognition Operating Lease Assets [Member]
Assets
Other assets	730
Derecognition Deferred Rent Current [Member]
Liabilities, stockholders’ equity and non-controlling interests
Accrued and other current liabilities	(619)
Derecognition Build to Suit Lease Liabilities Current [Member]
Liabilities, stockholders’ equity and non-controlling interests
Accrued and other current liabilities	(545)
Recognition Operating Lease Liabilities Current [Member]
Liabilities, stockholders’ equity and non-controlling interests
Accrued and other current liabilities	404
Recognition Finance Lease Liabilities Current [Member]
Liabilities, stockholders’ equity and non-controlling interests
Finance lease liabilities, current	11,499
Derecognition Build to Suit Lease Liabilities Non Current [Member]
Liabilities, stockholders’ equity and non-controlling interests
Long-term portion of lease obligations	(95,613)
Derecognition Deferred Rent Non Current [Member]
Liabilities, stockholders’ equity and non-controlling interests
Deferred rent	(3,038)
Recognition Finance Lease Liabilities Non Current [Member]
Liabilities, stockholders’ equity and non-controlling interests
Finance lease liabilities, non-current	49,884
Recognition Operating Lease Liabilities Non Current [Member]
Liabilities, stockholders’ equity and non-controlling interests
Other long-term liabilities	250
Cumulative Decrease to Accumulated Deficit [Member]
Liabilities, stockholders’ equity and non-controlling interests
Accumulated deficit	$ 8,688

Summary of Significant Accounting Policies - Schedule of Impacts to Accumulated Other Comprehensive Loss and Accumulated Deficit Upon Adoption of Guidance (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Accounting Policy [Line Items]
Accumulated other comprehensive loss	$ (224)		$ (2,281)
Accumulated deficit	$ (686,597)		$ (715,827)
ASU 2018-02 [Member]
Accounting Policy [Line Items]
Accumulated other comprehensive loss		$ (1,670)
Accumulated deficit		(716,438)
Impact of change in accounting principle upon adoption of ASU 2018-02 [Member] \| ASU 2018-02 [Member]
Accounting Policy [Line Items]
Accumulated other comprehensive loss		611
Accumulated deficit		$ (611)

Collaboration Agreements - Astellas Agreements - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended			9 Months Ended	12 Months Ended	35 Months Ended	45 Months Ended
	Sep. 30, 2019	Apr. 30, 2006	Jun. 30, 2005	Sep. 30, 2019	Dec. 31, 2018	Feb. 28, 2009	Feb. 28, 2009
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Unbilled contract asset	$ 180,000			$ 180,000	$ 0
Europe [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Unbilled contract asset	130,000			130,000
Astellas Agreement [Member] \| Japan [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront, non-contingent and time-based payments received							$ 40,100
Potential milestone payments	12,500		$ 132,500
Commercial sales milestone			15,000
Aggregate consideration received	77,600			77,600
Transaction price and allocated to performance obligations	12,500			12,500
Astellas Agreement [Member] \| Japan [Member] \| Clinical and Development Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			22,500
Astellas Agreement [Member] \| Japan [Member] \| Regulatory Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			$ 95,000
Astellas Agreement [Member] \| Europe [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront, non-contingent and time-based payments received						$ 320,000
Potential milestone payments		$ 425,000
Aggregate consideration received	410,000			410,000
Transaction price and allocated to performance obligations	130,000			$ 130,000
Percentage of joint development costs committed to fund		50.00%
Additional consideration based on net sales description				low 20% range
Estimated joint development extended service period					2023
Revenue during period from performance obligations	129,000			$ 129,000
Unbilled contract asset	$ 130,000			$ 130,000
Astellas Agreement [Member] \| Europe [Member] \| Clinical and Development Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments		$ 90,000
Astellas Agreement [Member] \| Europe [Member] \| Regulatory Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments		$ 335,000

Collaboration Agreements - AstraZeneca Agreements - Additional Information 1 (Detail) - USD ($) $ in Thousands				9 Months Ended	12 Months Ended
	Dec. 29, 2018	Dec. 17, 2018	Jul. 30, 2013	Sep. 30, 2019	Dec. 31, 2015	Jun. 30, 2019	Dec. 31, 2018
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Unbilled contract asset				$ 180,000			$ 0
AstraZeneca Agreements [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Transaction price and allocated to performance obligations						$ 50,000
Revenue during period from performance obligations				42,100
Unbilled contract asset				50,000
AstraZeneca Agreements [Member] \| U.S./RoW [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront, non-contingent, non-refundable and time-based payments			$ 374,000
Potential milestone payments			875,000
Commercial sales milestone			325,000
Aggregate consideration received				389,000
Unbilled contract asset				50,000
AstraZeneca Agreements [Member] \| U.S./RoW [Member] \| Clinical and Development Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			65,000
AstraZeneca Agreements [Member] \| U.S./RoW [Member] \| Regulatory Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			325,000
AstraZeneca Agreements [Member] \| U.S./RoW [Member] \| Deferred Approval Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			160,000
AstraZeneca Agreements [Member] \| U.S./RoW [Member] \| Development Milestones [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Receipt of development milestone payment					$ 15,000
AstraZeneca Agreements [Member] \| China [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			348,500
Aggregate consideration received				$ 55,200
Proceeds from upfront, non-contingent and non-refundable payments			28,200
Commercial sales and other events milestone			187,500
Estimated joint development extended service period				2024
Milestone payment, revenue recognition	$ 6,000	$ 6,000
AstraZeneca Agreements [Member] \| China [Member] \| Clinical and Development Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			15,000
AstraZeneca Agreements [Member] \| China [Member] \| Regulatory Milestone [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments			$ 146,000

Collaboration Agreements - Summary of Revenue Recognized under Agreement (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	$ 33,174	$ 29,027	$ 248,603	$ 104,903
License Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	11,935	0	162,517	14,323
Development Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	20,660	29,027	85,507	90,580
Astellas Agreement [Member] \| License Revenue [Member] \| Japan [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	11,935	0	11,935	14,323
Astellas Agreement [Member] \| License Revenue [Member] \| Europe [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	0	0	117,470	0
Astellas Agreement [Member] \| Development Revenue [Member] \| Japan [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	537	474	1,151	2,065
Astellas Agreement [Member] \| Development Revenue [Member] \| Europe [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	2,996	4,658	24,463	14,384
AstraZeneca Agreements [Member] \| China [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	19	0	19	0
AstraZeneca Agreements [Member] \| License Revenue [Member] \| U.S./RoW and China [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	0	0	33,112	0
AstraZeneca Agreements [Member] \| Development Revenue [Member] \| U.S./RoW and China [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Total revenue	$ 17,106	$ 23,895	$ 59,872	$ 74,096

Collaboration Agreements - Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations along with Associated Deferred Revenue (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Deferred Revenue	$ 53,988	$ 0
Astellas Agreement [Member] \| Japan [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	101,084
Deferred Revenue	312
Total Consideration	101,396
Astellas Agreement [Member] \| Japan [Member] \| Development Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	15,060
Deferred Revenue	312
Total Consideration	15,372
Astellas Agreement [Member] \| Japan [Member] \| License Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	86,024
Deferred Revenue	0
Total Consideration	86,024
Astellas Agreement [Member] \| Europe [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	715,251
Deferred Revenue	3,988
Total Consideration	719,239
Astellas Agreement [Member] \| Europe [Member] \| Development Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	227,300
Deferred Revenue	3,988
Total Consideration	231,288
Astellas Agreement [Member] \| Europe [Member] \| License Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	487,951
Deferred Revenue	0
Total Consideration	487,951
AstraZeneca Agreements [Member] \| U.S./RoW and China [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	795,803
Deferred Revenue	148,647
Total Consideration	944,450
AstraZeneca Agreements [Member] \| U.S./RoW and China [Member] \| License Revenue [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	327,275
Deferred Revenue	0
Total Consideration	327,275
AstraZeneca Agreements [Member] \| U.S./RoW and China [Member] \| Co-development, information sharing & committee services [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	468,509
Deferred Revenue	11,317
Total Consideration	479,826
AstraZeneca Agreements [Member] \| U.S./RoW and China [Member] \| China performance obligation [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Cumulative Revenue	19
Deferred Revenue	137,330
Total Consideration	$ 137,349

Collaboration Agreements - Summary of Revenue Recognized Under the Collaboration Agreements - Additional Information 4 (Detail) $ in Millions	3 Months Ended
	Sep. 30, 2019 USD ($)
Japan [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Remainder of transaction price, variable consideration from estimated future co-development billing	$ 0.2
Japan [Member] \| Astellas Agreement [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Changes in revenue due to prior period adjustment of performance obligations	12.3
Europe [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Remainder of transaction price, variable consideration from estimated future co-development billing	42.4
Europe [Member] \| Astellas Agreement [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Changes in revenue due to prior period adjustment of performance obligations	2.9
U.S./RoW and China [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Remainder of transaction price, variable consideration from estimated future co-development billing	186.6
U.S./RoW and China [Member] \| AstraZeneca Agreements [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Changes in revenue due to prior period adjustment of performance obligations	$ 3.5

Collaboration Agreements - Transaction Price Related to Consideration Received and Accounts Receivable Allocated to Performance Obligations along with Associated Deferred Revenue (Parenthetical) (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Unbilled contract asset	$ 180,000	$ 0
Deferred revenue	53,988	0
Net unbilled contract asset	126,012	0
Long-term deferred revenue	98,708	$ 136,109
Europe [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Unbilled contract asset	130,000
Astellas Agreement [Member] \| Europe [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Unbilled contract asset	130,000
Deferred revenue	3,988
Astellas Agreement [Member] \| Europe [Member] \| Prepaid Expenses and Other Current Assets [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Net unbilled contract asset	126,000
AstraZeneca Agreements [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Unbilled contract asset	50,000
AstraZeneca Agreements [Member] \| U.S./RoW [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Unbilled contract asset	50,000
Deferred revenue	148,600
Net unbilled contract asset	50,000
Long-term deferred revenue	$ 98,600

Collaboration Agreements - Product Revenue - Additional Information 4 (Detail) $ in Millions	3 Months Ended
	Sep. 30, 2019 USD ($)
Product Revenue [Member] \| China [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Contract with customer, liability, revenue recognized	$ 0.6

Collaboration Agreements - Deferred Revenue - Additional Information (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Contract with Customer, Liability [Abstract]
Deferred revenue	$ 53,988	$ 0
AstraZeneca Agreements [Member] \| China [Member]
Contract with Customer, Liability [Abstract]
Deferred revenue	$ 700

Fair Value Measurements - Fair Values of Financial Liabilities Carried at Historical Cost (Detail) - Lease obligations [Member] - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities fair value disclosure	$ 1,645	$ 98,105
Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities fair value disclosure	0	0
Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities fair value disclosure	0	0
Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities fair value disclosure	$ 1,645	$ 98,105

Fair Value Measurements - Additional Information (Detail) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Lease payment liability	$ 52,862,000
Transfers of assets from level 1 to 2	0	$ 0
Transfers of assets from level 2 to 1	0	0
Transfers of liabilities from level 1 to 2	0	0
Transfers of liabilities from level 2 to 1	0	0
Transfers of assets into level 3	0	0
Transfers of assets out of level 3	0	0
Transfers of liabilities into level 3	0	0
Transfers of liabilities out of level 3	$ 0	0
Shorenstein Properties LLC [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Lease commencement date	2008
Lease payment liability	$ 5,000,000.0
Remaining lease term	2023
Building [Member] \| Shorenstein Properties LLC [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Lease maximum expansion period	31 months
Lease obligations [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities fair value disclosure	$ 1,645,000	98,105,000
Lease obligations [Member] \| Long-term property lease [Member] \| Shorenstein Properties LLC [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities fair value disclosure	$ 1,600,000
Lease obligations [Member] \| Building [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liabilities fair value disclosure		$ 96,200,000

Leases - Additional Information (Detail) - Lease	9 Months Ended	12 Months Ended
Leases - Additional Information (Detail) - Lease	Sep. 30, 2019	Dec. 31, 2013	Dec. 31, 2006
Minimum [Member]
Lessee Lease Description [Line Items]
Lessee, operating lease, lease term	2 years
Maximum [Member]
Lessee Lease Description [Line Items]
Lessee, operating lease, lease term	4 years
Shorenstein Properties LLC [Member]
Lessee Lease Description [Line Items]
Lessee, finance lease, initial lease term			15 years
Lessee, finance lease, expiration period			2023
Lessee, finance lease, option to extend the additional lease term			10 years
Lessee, finance lease, additional lease expiration period			2033
Percentage increases on each anniversary of rent commencement date			2.00%
Lessee, finance lease, existence of option to extend			true
Lessee, finance lease, option to extend	The Company has an option to extend the lease for an additional 10 years through 2033.
Beijing Economic-Technological Development Area [Member]
Lessee Lease Description [Line Items]
Lessee, finance lease, initial lease term		8 years
Lessee, finance lease, expiration period		2021
Lessee, finance lease, existence of option to extend		false
Building [Member]
Lessee Lease Description [Line Items]
Number of finance leases	2
Number of operating leases	6
Office Equipment [Member] \| Minimum [Member]
Lessee Lease Description [Line Items]
Lessee, operating lease, lease term	2 years
Office Equipment [Member] \| Maximum [Member]
Lessee Lease Description [Line Items]
Lessee, operating lease, lease term	5 years

Leases - Schedule of Lease Assets and Related Lease Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Leases [Abstract]
Right-of-use assets - cost	$ 49,784
Accumulated amortization	(7,720)
Finance lease right-of-use assets, net	42,064	$ 0
Right-of-use assets - cost	2,723
Accumulated amortization	(531)
Operating lease right-of-use assets, net	2,192
Total lease assets	44,256
Finance lease liabilities	12,149	0
Operating lease liabilities	998
Finance lease liabilities	40,713	$ 0
Operating lease liabilities	1,133
Total lease liabilities	$ 54,993

Leases - Components of Lease Expense (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2018
Finance lease cost:
Amortization of right-of-use assets	$ 2,580	$ 7,720	$ 0
Interest on lease liabilities	578	1,826
Operating lease cost	290	579
Sublease income	(310)	(1,135)
Total lease cost	$ 3,138	$ 8,990

Leases - Schedule of Supplemental Cash Flow Information Related to Leases (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 540
Operating cash flows from finance leases	1,640
Financing cash flows from finance leases	8,810	$ 0
Right-of-use assets obtained in exchange for new lease liabilities:
Finance leases	49,784
Operating leases	$ 2,723

Leases - Schedule of Lease Term and Discount Rate (Detail)	Sep. 30, 2019
Weighted-average remaining lease term (years):
Finance leases	3 years 9 months 18 days
Operating leases	2 years 3 months 18 days
Weighted-average discount rate:
Finance leases	4.43%
Operating leases	4.75%

Leases - Schedule of Maturities of Lease Liabilities (Detail) $ in Thousands	Sep. 30, 2019 USD ($)
Finance Leases
2019 (Remaining three month period)	$ 3,466
2020	14,060
2021	13,675
2022	13,878
2023	12,523
Total future lease payments	57,602
Less: Interest	(4,740)
Present value of lease liabilities	52,862
Operating Leases
2019 (Remaining three month period)	280
2020	1,013
2021	651
2022	300
2023	0
Total future lease payments	2,244
Less: Interest	(113)
Present value of lease liabilities	$ 2,131

Leases - Schedule of Future Minimum Lease Payments Under all Non-Cancelable Operating Lease Obligations (Detail) $ in Thousands	Dec. 31, 2018 USD ($)
Leases [Abstract]
2019	$ 444
2020	232
2021	25
2022	16
2023	0
Total minimum payments	$ 717

Leases - Schedule of Future Minimum Lease Payments on Consolidated Basis Under Company's Facility Financing Lease Obligations (Detail) $ in Thousands	Dec. 31, 2018 USD ($)
Leases [Abstract]
2019	$ 14,379
2020	14,664
2021	14,179
2022	14,335
2023	12,872
Total minimum payments	$ 70,429

Balance Sheet Components - Schedule of Cash and Cash Equivalents (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Cash And Cash Equivalents [Abstract]
Cash	$ 90,770	$ 38,783
US treasury notes and bills	0	49,934
Money market funds	105,822	541
Total cash and cash equivalents	$ 196,592	$ 89,258

Balance Sheet Components - Additional Information (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) Milestone	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Cash and cash equivalents	$ 196,592,000		$ 196,592,000		$ 89,258,000
Contractual maturities of available-for-sale investments			1 year
Other-than-temporary impairment loss	0	$ 0	$ 0	$ 0
Provision to write-down excess and obsolete inventory	0		$ 0
Number of regulatory milestones \| Milestone			2
Unbilled contract assets	180,000,000		$ 180,000,000		0
Building shell cost	142,310,000		142,310,000		192,397,000
Accumulated depreciation	99,102,000		99,102,000		65,199,000
Building shell [Member]
Schedule of Available-for-sale Securities [Line Items]
Building shell cost	0		0		53,880,000
Building [Member] \| Build to suit arrangements [Member]
Schedule of Available-for-sale Securities [Line Items]
Accumulated depreciation					13,500,000
Leasehold improvements [Member]
Schedule of Available-for-sale Securities [Line Items]
Building shell cost	101,339,000		101,339,000		101,200,000
Leasehold improvements [Member] \| Accounting standards update 2016-02 [Member]
Schedule of Available-for-sale Securities [Line Items]
Accumulated depreciation	38,900,000		38,900,000
Europe [Member]
Schedule of Available-for-sale Securities [Line Items]
Unbilled contract assets	130,000,000.0		130,000,000.0
Astellas Agreement [Member] \| Europe [Member]
Schedule of Available-for-sale Securities [Line Items]
Unbilled contract assets	130,000,000.0		130,000,000.0
AstraZeneca Agreements [Member]
Schedule of Available-for-sale Securities [Line Items]
Unbilled contract assets	50,000,000.0		50,000,000.0
AstraZeneca Agreements [Member] \| U.S./RoW [Member]
Schedule of Available-for-sale Securities [Line Items]
Unbilled contract assets	50,000,000.0		50,000,000.0
Foreign subsidiaries [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and cash equivalents	$ 18,100,000		$ 18,100,000		$ 21,900,000

Balance Sheet Components - Summary of Amortized Cost, Gross Unrealized Holding Gains or Losses, and Fair Value of Available-for-Sale Investments (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 442,170	$ 587,885
Gross Unrealized Holding Gains	894	238
Gross Unrealized Holding Losses	(25)	(159)
Fair Value	443,039	587,964
US treasury notes and bills [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	401,377	467,296
Gross Unrealized Holding Gains	688	109
Gross Unrealized Holding Losses	(25)	(69)
Fair Value	402,040	467,336
Term deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		80,000
Gross Unrealized Holding Gains		0
Gross Unrealized Holding Losses		0
Fair Value		80,000
Certificate of deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	30,000	30,000
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	0	(90)
Fair Value	30,000	29,910
Bond and mutual funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	10,668	10,464
Gross Unrealized Holding Gains	80	20
Gross Unrealized Holding Losses	0	0
Fair Value	10,748	10,484
Equity investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	125	125
Gross Unrealized Holding Gains	126	109
Gross Unrealized Holding Losses	0	0
Fair Value	$ 251	$ 234

Balance Sheet Components - Schedule of Inventory (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Schedule Of Investments [Abstract]
Raw materials			$ 658
Work-in-progress			1,155
Finished goods			3,095
Total inventories	$ 4,908	$ 0	$ 4,908

Balance Sheet Components - Schedule of Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Prepaid Expense And Other Assets Current [Abstract]
Unbilled contract assets	$ 180,000	$ 0
Deferred revenues from associated contracts	(53,988)	0
Net unbilled contract assets	126,012	0
Prepaid assets	4,051	2,705
Other current assets	3,652	2,224
Total prepaid expenses and other current assets	$ 133,715	$ 4,929

Balance Sheet Components - Schedule of Property and Equipment (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 142,310	$ 192,397
Less: accumulated depreciation	(99,102)	(65,199)
Property and equipment, net	43,208	127,198
Leasehold improvements [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	101,339	101,200
Building shell [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	0	53,880
Laboratory Equipment [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	16,932	16,405
Machinery [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	8,691	8,382
Computer Equipment [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	7,227	6,473
Furniture and Fixtures [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	5,789	5,690
Construction in progress [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 2,332	$ 367

Balance Sheet Components - Schedule of Accrued Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Accrued Liabilities Current [Abstract]
Preclinical and clinical trial accruals	$ 41,546	$ 35,413
Payroll and related accruals	17,604	21,430
Property taxes and other	2,389	1,095
Professional services	4,063	2,648
Other	5,223	5,537
Total accrued liabilities	$ 70,825	$ 66,123

Stock-Based Compensation - Schedule of Allocated Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 14,793	$ 14,323	$ 48,865	$ 38,432
Research and development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	10,185	8,465	30,214	22,729
Selling, general and administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 4,608	$ 5,858	$ 18,651	$ 15,703

Stock-Based Compensation - Schedule of Assumptions used to Estimate Fair Value of Stock Options Granted and Purchases under 2014 Employee Share Purchase Plan (Detail) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Employee stock options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	5 years 3 months 18 days	5 years 3 months 18 days	5 years 3 months 18 days	5 years 4 months 24 days
Expected volatility	67.80%	68.10%	67.90%	67.80%
Risk-free interest rate	1.70%	2.90%	2.40%	2.70%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Weighted average estimated fair value	$ 25.17	$ 35.99	$ 32.44	$ 32.37
2014 Employee Share Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility, minimum	48.10%	47.30%	48.10%	47.30%
Expected volatility, maximum	62.10%	75.30%	62.10%	75.30%
Risk-free interest rate, minimum	1.30%	0.80%	1.30%	0.80%
Risk-free interest rate, maximum	2.90%	2.60%	2.90%	2.60%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Weighted average estimated fair value	$ 19.27	$ 20.10	$ 19.53	$ 15.27
2014 Employee Share Purchase Plan [Member] \| Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 months	6 months	6 months	6 months
2014 Employee Share Purchase Plan [Member] \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	2 years	2 years	2 years	2 years

Related Party Transactions - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Related Party Transaction [Line Items]
Accounts receivable from related party	$ 17,662,000		$ 17,662,000		$ 47,210,000
Accrued liabilities to related party	954,000		954,000		444,000
Unbilled contract asset	180,000,000		180,000,000		0
Due from Related Parties, Current	126,012,000		126,012,000		0
Net unbilled contract asset	126,012,000		126,012,000		0
Deferred Revenue	53,988,000		53,988,000		0
Europe [Member]
Related Party Transaction [Line Items]
Unbilled contract asset	130,000,000.0		130,000,000.0
Astellas Agreement [Member] \| Europe [Member]
Related Party Transaction [Line Items]
Unbilled contract asset	130,000,000.0		130,000,000.0
Deferred Revenue	3,988,000		3,988,000
Astellas [Member] \| Europe [Member]
Related Party Transaction [Line Items]
Unbilled contract asset	130,000,000.0		130,000,000.0
Net unbilled contract asset	126,000,000.0		126,000,000.0
Deferred Revenue	4,000,000.0		4,000,000.0
Astellas [Member] \| Collaborative Arrangement [Member]
Related Party Transaction [Line Items]
Revenue related to collaboration agreements	15,500,000	$ 5,100,000	155,000,000.0	$ 30,800,000
Expense related to collaboration agreements	900,000	$ 400,000	2,200,000	$ 1,100,000
Accounts receivable from related party	17,700,000		17,700,000		47,200,000
Accrued liabilities to related party	1,700,000		1,700,000		400,000
Astellas [Member] \| Astellas Agreement [Member] \| Milestone Payment [Member]
Related Party Transaction [Line Items]
Accrued liabilities to related party	$ 12,500,000		$ 12,500,000
Astellas [Member] \| Astellas Agreement [Member] \| Active Pharmaceutical Ingredients Shipment [Member]
Related Party Transaction [Line Items]
Accrued liabilities to related party					$ 43,800,000

Fair Value Measurements - Fair Values of Financial Assets Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	$ 443,039	$ 587,964
US treasury notes and bills [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	402,040	467,336
Bond and mutual funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	10,748	10,484
Equity investments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	251	234
Term deposit [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments		80,000
Certificate of deposit [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	30,000	29,910
Fair Value, Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	548,861	638,439
Fair Value, Measurements, Recurring [Member] \| US treasury notes and bills [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	402,040	517,270
Fair Value, Measurements, Recurring [Member] \| Bond and mutual funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	10,748	10,484
Fair Value, Measurements, Recurring [Member] \| Equity investments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	251	234
Fair Value, Measurements, Recurring [Member] \| Money market funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets fair value disclosure	105,822	541
Fair Value, Measurements, Recurring [Member] \| Term deposit [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments		80,000
Fair Value, Measurements, Recurring [Member] \| Certificate of deposit [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	30,000	29,910
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	343,411	303,576
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member] \| US treasury notes and bills [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	226,590	292,317
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member] \| Bond and mutual funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	10,748	10,484
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member] \| Equity investments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	251	234
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member] \| Money market funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets fair value disclosure	105,822	541
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member] \| Term deposit [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments		0
Fair Value, Measurements, Recurring [Member] \| Level 1 [Member] \| Certificate of deposit [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	205,450	334,863
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| US treasury notes and bills [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	175,450	224,953
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Bond and mutual funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Equity investments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Money market funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets fair value disclosure	0	0
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Term deposit [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments		80,000
Fair Value, Measurements, Recurring [Member] \| Level 2 [Member] \| Certificate of deposit [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	30,000	29,910
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value of financial assets	0	0
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member] \| US treasury notes and bills [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member] \| Bond and mutual funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member] \| Equity investments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member] \| Money market funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets fair value disclosure	0	0
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member] \| Term deposit [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments		0
Fair Value, Measurements, Recurring [Member] \| Level 3 [Member] \| Certificate of deposit [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments	$ 0	$ 0