ChemoCentryx (CCXI) 10-K 1 Mar 21 2020 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2020	Feb. 22, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Entity Registrant Name	ChemoCentryx, Inc.
Entity Central Index Key	0001340652
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Interactive Data Current	Yes
Entity File Number	001-35420
Entity Tax Identification Number	94-3254365
Entity Address, Address Line One	850 Maude Avenue
Entity Address, City or Town	Mountain View
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94043
City Area Code	650
Local Phone Number	210-2900
Trading Symbol	CCXI
Entity Incorporation, State or Country Code	DE
Security Exchange Name	NASDAQ
Title of 12(b) Security	Common Stock, par value $0.001 per share
Entity Common Stock, Shares Outstanding		69,613,267
Entity Public Float			$ 1.9
Document Annual Report	true
Document Transition Report	false
ICFR Auditor Attestation Flag	true
Documents Incorporated by Reference	Portions of the registrant’s definitive proxy statement to be filed with the Securities and Exchange Commission pursuant to Regulation 14A in connection with the registrant’s 2021 Annual Meeting of Stockholders, which will be filed subsequent to the date hereof, are incorporated by reference into Part III of this Annual Report on Form 10-K. Such proxy statement will be filed with the Securities and Exchange Commission not later than 120 days following the end of the registrant’s fiscal year ended December 31, 2020.

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 32,297	$ 39,179
Short-term investments	404,273	133,607
Accounts receivable, other	137	176
Accounts receivable from related party	32	0
Prepaid expenses and other current assets	4,831	1,400
Total current assets	441,570	174,362
Property and equipment, net	25,160	2,154
Long-term investments	23,800	29,454
Operating lease right-of-use assets	26,911	1,704
Other assets	1,458	1,409
Total assets	518,899	209,083
Current liabilities:
Accounts payable	12,875	1,532
Accrued and other current liabilities	19,794	19,806
Long-term debt, current	6,302	0
Deferred revenue from related party	12,587	37,742
Total current liabilities	51,558	59,080
Long-term debt, net	18,099	19,786
Non-current deferred revenue from related party	24,000	63,095
Non-current lease liabilities	38,671	566
Other non-current liabilities	958	556
Total liabilities	133,286	143,083
Commitments (Note 8)
Stockholders’ equity:
Preferred stock, $0.001 par value, 10,000,000 shares authorized; no shares issued and outstanding	0	0
Common stock, $0.001 par value, 200,000,000 shares authorized; 69,452,466 and 60,234,784 shares issued and outstanding at December 31, 2020 and 2019, respectively	69	60
Additional paid-in capital	870,788	495,624
Note receivable	(16)	(16)
Accumulated other comprehensive income	114	318
Accumulated deficit	(485,342)	(429,986)
Total stockholders’ equity	385,613	66,000
Total liabilities and stockholders’ equity	$ 518,899	$ 209,083

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	69,452,466	60,234,784
Common stock, shares outstanding	69,452,466	60,234,784

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue:
Collaboration and license revenue from related party	$ 64,392	$ 35,952	$ 42,875
Grant revenue	499	176	0
Total revenue	64,891	36,128	42,875
Operating expenses:
Research and development	77,882	70,276	62,736
General and administrative	42,186	24,155	20,409
Total operating expenses	120,068	94,431	83,145
Loss from operations	(55,177)	(58,303)	(40,270)
Other income (expense):
Interest income	2,464	4,963	3,528
Interest expense	(2,643)	(2,149)	(1,224)
Total other income (expense), net	(179)	2,814	2,304
Net loss	$ (55,356)	$ (55,489)	$ (37,966)
Net loss per common share
Basic and diluted net loss per common share	$ (0.84)	$ (0.98)	$ (0.76)
Shares used to compute basic and diluted net loss per common share	65,688	56,898	49,814

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (55,356)	$ (55,489)	$ (37,966)
Unrealized gain (loss) on available-for-sale securities	(204)	516	(79)
Comprehensive loss	$ (55,560)	$ (54,973)	$ (38,045)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Cumulative Effect Period Of Adoption Adjustment [Member]	Common Stock [Member]	Common Stock [Member]Cumulative Effect Period Of Adoption Adjustment [Member]	Additional Paid-In Capital [Member]	Additional Paid-In Capital [Member]Cumulative Effect Period Of Adoption Adjustment [Member]	Note Receivable [Member]	Note Receivable [Member]Cumulative Effect Period Of Adoption Adjustment [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Other Comprehensive Income (Loss) [Member]Cumulative Effect Period Of Adoption Adjustment [Member]	Accumulated Deficit [Member]	Accumulated Deficit [Member]Cumulative Effect Period Of Adoption Adjustment [Member]
Beginning Balance at Dec. 31, 2017	$ 79,267		$ 49		$ 368,553		$ (16)		$ (119)		$ (289,200)
Beginning Balance, shares at Dec. 31, 2017			48,837,060
Net loss	(37,966)		$ 0		0		0		0		(37,966)
Adoption of accounting standards (Note 2)		$ (47,331)		$ 0		$ 0		$ 0		$ 0		$ (47,331)
Unrealized [gain/loss] on investments	(79)		0		0		0		(79)		0
Issuance of common stock under equity incentive and employee stock purchase plans	10,692		$ 2		10,690		0		0		0
Issuance of common stock under equity incentive and employee stock purchase plans, shares			1,912,703
Repurchased shares upon vesting of restricted stock units for tax withholdings	(678)		$ 0		(678)		0		0		0
Repurchased shares upon vesting of restricted stock units for tax withholdings, shares			(97,525)
Employee stock-based compensation	9,971		$ 0		9,971		0		0		0
Compensation expense related to options granted to consultants	862		0		862		0		0		0
Ending Balance at Dec. 31, 2018	14,738		$ 51		389,398		(16)		(198)		(374,497)
Ending Balance, shares at Dec. 31, 2018			50,652,238
Net loss	(55,489)		$ 0		0		0		0		(55,489)
Unrealized [gain/loss] on investments	516		0		0		0		516		0
Issuance of common stock throughEquity Distribution Agreement,net of issuance costs (Note 11)	$ 73,276		$ 6		73,270		0		0		0
Issuance of common stock throughEquity Distribution Agreement,net of issuance costs (Note 11), shares	6,491,196		6,491,196
Issuance of common stock under equity incentive and employee stock purchase plans	$ 22,634		$ 3		22,631		0		0		0
Issuance of common stock under equity incentive and employee stock purchase plans, shares			3,216,876
Repurchased shares upon vesting of restricted stock units for tax withholdings	(1,313)		$ 0		(1,313)		0		0		0
Repurchased shares upon vesting of restricted stock units for tax withholdings, shares			(125,526)
Employee stock-based compensation	11,349		$ 0		11,349		0		0		0
Compensation expense related to options granted to consultants	289		0		289		0		0		0
Ending Balance at Dec. 31, 2019	$ 66,000		$ 60		495,624		(16)		318		(429,986)
Ending Balance, shares at Dec. 31, 2019	60,234,784		60,234,784
Net loss	$ (55,356)		$ 0		0		0		0		(55,356)
Unrealized [gain/loss] on investments	(204)		0		0		0		(204)		0
Issuance of common stock throughEquity Distribution Agreement,net of issuance costs (Note 11)	325,654		$ 6		325,648		0		0		0
Issuance of common stock throughEquity Distribution Agreement,net of issuance costs (Note 11), shares			5,980,000
Issuance of common stock under equity incentive and employee stock purchase plans	30,316		$ 3		30,313		0		0		0
Issuance of common stock under equity incentive and employee stock purchase plans, shares			3,330,141
Repurchased shares upon vesting of restricted stock units for tax withholdings	(3,709)		$ 0		(3,709)		0		0		0
Repurchased shares upon vesting of restricted stock units for tax withholdings, shares			(92,459)
Employee stock-based compensation	20,948		$ 0		20,948		0		0		0
Compensation expense related to options granted to consultants	1,964		0		1,964		0		0		0
Ending Balance at Dec. 31, 2020	$ 385,613		$ 69		$ 870,788		$ (16)		$ 114		$ (485,342)
Ending Balance, shares at Dec. 31, 2020	69,452,466		69,452,466

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating activities
Net loss		$ (55,356)	$ (55,489)	$ (37,966)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Stock-based compensation		22,912	11,638	10,833
Depreciation of property and equipment		797	550	512
Non-cash lease expense		1,970	1,092	0
Non-cash interest (income) expense, net		1,490	(1,499)	(1,071)
Changes in assets and liabilities:
Accounts receivable, other		39	(176)	0
Accounts receivable from related party		(32)	2,058	49,032
Prepaids and other current assets		(2,492)	719	(668)
Other assets		(49)	61	(31)
Accounts payable		2,982	188	(434)
Operating lease liabilities		10,270	(1,114)	0
Other liabilities		576	5,573	4,158
Deferred revenue from related party		(64,250)	(33,724)	(7,929)
Net cash (used in) provided by operating activities		(81,143)	(70,123)	16,436
Investing activities
Purchases of property and equipment, net		(15,409)	(790)	(838)
Purchases of investments		(445,671)	(211,973)	(192,480)
Sales of investments		0	4,967	0
Maturities of investments		178,720	195,270	140,250
Net cash used in investing activities		(282,360)	(12,526)	(53,068)
Financing activities
Proceeds from issuance of common stock		325,654	73,276	0
Proceeds from exercise of stock options and employee stock purchase plan		30,318	22,857	10,467
Employees' tax withheld and paid for restricted stock units		(3,709)	(1,313)	(678)
Borrowings under credit facility agreement, net of issuance costs		4,358	0	14,911
Net cash provided by financing activities		356,621	94,820	24,700
Net increase (decrease) in cash, cash equivalents and restricted cash		(6,882)	12,171	(11,932)
Cash, cash equivalents and restricted cash at beginning of period		40,259	28,088	40,020
Cash, cash equivalents and restricted cash at end of period		33,377	40,259	28,088
Supplemental disclosures of cash flow information
Cash paid for interest		1,947	1,735	748
Right-of-use assets obtained in exchange for lease obligations	[1]	27,177	2,796	0
Purchases of property and equipment, net recorded in accounts payable and accrued liabilities		$ 8,394	$ 378	$ 0
[1]	Amounts for the year ended December 31, 2019 include the transition adjustment of $1,301 for the adoption of Accounting Standards Codification (ASC) Topic 842 Leases ( ASC 842).

Consolidated Statements of Ca_2

Consolidated Statements of Cash Flows (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Right-of-use assets obtained in exchange for lease obligations	$ 2,796	[1]
Accounting Standards Update 2016-02 [Member]
Right-of-use assets obtained in exchange for lease obligations	$ 1,301
[1]	Amounts for the year ended December 31, 2019 include the transition adjustment of $1,301 for the adoption of Accounting Standards Codification (ASC) Topic 842 Leases ( ASC 842).

Description of Business

Description of Business	12 Months Ended
	Dec. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Description of Business	1. Description of Business ChemoCentryx, Inc. (the Company) commenced operations in 1997. The Company is a biopharmaceutical company focused on the development and commercialization of new medications targeting inflammatory disorders, autoimmune diseases and cancer. The Company’s principal operations are in the United States and it operates in one segment.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The consolidated financial statements are prepared in conformity with accounting principles generally accepted in the United States (GAAP). The consolidated financial statements include the Company’s accounts and those of its wholly owned subsidiaries, ChemoCentryx Ireland Limited and ChemoCentryx Limited. The operations of ChemoCentryx Ireland Limited and ChemoCentryx Limited have been immaterial to date. All intercompany amounts have been eliminated in consolidation. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from these estimates. Cash Equivalents and Investments The Company considers all highly liquid investments with an original maturity at the date of purchase of three months or less to be cash equivalents. The Company limits its concentration of risk by diversifying its investments among a variety of issuers. All investments are classified as available for sale and are recorded at fair value based on quoted prices in active markets or based upon other observable inputs, with unrealized gains and losses excluded from earnings and reported in other comprehensive income (loss). Purchase premiums and discounts are recognized in interest income using the interest method over the terms of the securities. Realized gains and losses and unrealized declines in fair value that are attributed to credit-related factors are reflected in the statement of operations. The cost of securities sold is based on the specific-identification method. Fair Value of Financial Instruments The carrying amounts of certain of the Company’s financial instruments, including cash and cash equivalents, short-term investments, accounts receivable and accounts payable, approximate their fair value due to their short maturities. 2. Summary of Significant Accounting Policies (continued) Fair value is considered to be the price at which an asset could be exchanged or a liability transferred (an exit price) in an orderly transaction between knowledgeable, willing parties in the principal or most advantageous market for the asset or liability. Where available, fair value is based on or derived from observable market prices or other observable inputs. Where observable prices or inputs are not available, valuation models are applied. The valuation techniques involve management estimation and judgment, the degree of which is dependent on the price transparency for the instruments or market and the instruments’ complexity. Concentration of Credit Risk The Company invests in a variety of financial instruments and, by its policy, limits the amount of credit exposure with any one issuer, industry or geographic area. For the years ended December 31, 2020, 2019 and 2018, 99.2%%, 99.5% and 100%, respectively, of the Company’s total revenue was derived from the Company’s collaboration with Vifor (International) Ltd., and/or its affiliates, or collectively, Vifor. Property and Equipment Property and equipment are stated at cost less accumulated depreciation. Depreciation is calculated using the straight-line method over the estimated useful lives of the assets, which range from five to seven years. Tenant improvements are depreciated over the lesser of the estimated useful life or the remaining life of the lease at the time the asset is placed into service. Impairment of Long-Lived Assets The Company reviews long-lived assets, including property and equipment, for impairment whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. An impairment loss would be recognized when estimated undiscounted future cash flows expected to result from the use of an asset are less than its carrying amount. The impairment loss would be based on the excess of the carrying value of the impaired asset over its respective fair value. To date, the Company has not recorded any impairment losses. 2. Summary of Significant Accounting Policies (continued) Leases Effective January 1, 2019, the Company adopted ASC 842 using the modified retrospective approach. Amounts presented prior to the adoption of ASC 842 have not been adjusted and continue to be reported in accordance with the Company’s historical accounting under previous lease guidance, ASC Topic 840, Leases (ASC 840). The Company determines if an arrangement includes a lease at inception. Operating leases are included in operating lease right-of-use (ROU) assets, accrued and other current liabilities and other non-current liabilities on the Company’s Condensed Consolidated Balance Sheets. Operating lease ROU assets and operating lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at commencement date. The Company uses the incremental borrowing rate based on the information available at lease commencement date in determining the present value of future payments. The operating lease ROU asset also excludes lease incentives. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise any such options. Lease expense for minimum lease payments is recognized on a straight-line basis over the lease term. The Company has elected not to apply the recognition requirements for short-term leases. For lease agreements with lease and non-lease components, the Company generally accounts for them separately. Revenue Recognition Effective January 1, 2018, the Company adopted ASC Topic 606, Revenue from Contracts with Customers The Company enters into corporate collaborations under which it may obtain upfront license fees, research and development funding and development and regulatory and commercial milestone payments and royalty payments. The Company’s performance obligations under these arrangements may include licenses of intellectual property, distribution rights, research and development services, delivery of manufactured product, and/or participation on joint steering committees. Licenses of intellectual property: If the license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenue from upfront license fees allocated to the license when the license is transferred to the customer and the customer is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgement to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring proportional performance for purposes of recognizing revenue from non-refundable, up-front fees. The Company evaluates the measure of proportional performance each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. 2. Summary of Significant Accounting Policies (continued) Milestone payments: At the inception of each arrangement that includes development, regulatory or commercial milestone payments, the Company evaluates whether the milestones are considered probable of being reached and estimates the amount to be included in the transaction price. There are two alternatives to use when estimating the amount of variable consideration: the expected value method and the most likely amount method. Under the expected value method, an entity considers the sum of probability-weighted amounts in a range of possible consideration amounts. Under the most likely amount method, an entity considers the single most likely amount in a range of possible consideration amounts. Whichever method is used, it should be consistently applied throughout the life of the contract; however, it is not necessary for the Company to use the same approach for all contracts. The Company expects to use the most likely amount method for development and regulatory milestone payments. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the Company’s or the licensee’s control, such as regulatory approvals, are not considered probable of being achieved until those approvals are received. The transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis. The Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, the Company re-evaluates the probability of achievement of each such milestone and any related constraint, and if necessary, adjusts its estimates of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenues and earnings in the period of adjustment. Commercial milestones and royalties: For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and in which the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue when the related sales occur. To date, the Company has not recognized any royalty revenue resulting from its collaboration arrangements. Up-front payments and fees are recorded as deferred revenue upon receipt or when due, and may require deferral of revenue recognition to a future period until the Company performs its obligations under these arrangements. Amounts payable to the Company are recorded as accounts receivable when the Company’s right to consideration is unconditional. Upon adoption of ASC 606 under the modified retrospective transition method, the Company recognized the cumulative effect of initially applying the new revenue standard of $47.3 million as an adjustment to the opening balance of accumulated deficit and an increase in deferred revenue. Revenue from government and private agency grants is recognized as the related research and development expenses are incurred and to the extent that funding is approved. Research and Development Expenses All research and development expenses are recognized as incurred. Research and development expenses include, but are not limited to, salaries and related benefits, including stock-based compensation, third-party contract costs relating to research, formulation, manufacturing, preclinical study and clinical trial activities, laboratory consumables and allocated facility costs. Clinical Trial Accruals Clinical trial costs are a component of research and development expenses. The Company accrues and expenses clinical trial activities performed by third parties based upon estimates of the percentage of work completed over the life of the individual study in accordance with agreements established with clinical research organizations and clinical trial sites. The Company determines the estimates through discussions with internal clinical personnel and external service providers as to the progress or stage of completion of trials or services and the agreed-upon fee to be paid for such services. Nonrefundable advance payments for goods and services that will be used or rendered in future research and development activities, are deferred and recognized as expense in the period that the related goods are delivered or services are performed. 2. Summary of Significant Accounting Policies (continued) Stock-Based Compensation The Company measures stock-based compensation cost at the grant date based on the fair value of the award, and recognizes the expense over the award’s vesting periods on a straight-line basis. The fair value of a stock option is estimated using the Black-Scholes valuation model, which requires that, at the date of grant, assumptions are made with respect to the expected life of the option, the volatility of the fair value of the Company’s common stock, the risk-free interest rate and the expected dividend yield of the Company’s common stock. The fair value of a restricted stock unit (RSU) and restricted stock award (RSA) is valued at the closing price of the Company’s common stock on the date of the grant. Because stock compensation expense is based on awards ultimately expected to vest, it has been reduced by an estimate for future forfeitures. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. On January 1, 2019 the Company adopted Accounting Standards Update (ASU) No. 2018-07, Compensation – Stock Compensation Comprehensive Loss Comprehensive loss comprises net loss and other comprehensive income (loss). For the periods presented, other comprehensive income (loss) consists of unrealized gains (losses) on the Company’s available-for-sale securities. For the year ended December 31, 2019, amounts reclassified from accumulated other comprehensive income (loss) to net loss for unrealized gains on available-for-sale securities were not significant, and were recorded as part of other income, net in the Consolidated Statements of Operations. For the years ended December 31, 2020 and 2018, there were no sales of investments, and therefore there were no reclassifications Income Taxes The Company uses the liability method for income taxes, whereby deferred tax assets and liabilities are determined based on the differences between the financial reporting and tax reporting bases of assets and liabilities and are measured using enacted tax rates and laws that are expected to be in effect when the differences are expected to reverse. Valuation allowances are provided when the expected realization for the deferred tax assets does not meet the more-likely-than-not criteria. The Company accounts for uncertain tax positions in the financial statements when it is not more likely than not that the position will be sustained upon examination by the tax authorities. Such tax positions must initially and subsequently be measured at the largest amount of tax benefit that has a greater than 50% likelihood of being realized upon ultimate settlement with the tax authority assuming full knowledge of the position and relevant facts. The Company’s policy is to recognize any interest and penalties related to unrecognized tax benefits in income tax expense. 2. Summary of Significant Accounting Policies (continued) Net Loss Per Share Basic net loss per common share is computed by dividing net loss attributable to common stockholders by the weighted-average number of common shares outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share is computed by dividing net loss attributable to common stockholders by the sum of the weighted-average number of common shares outstanding and dilutive common stock equivalent shares outstanding for the period. The Company’s potentially dilutive common stock equivalent shares, which include incremental common shares issuable upon (i) the exercise of outstanding stock options and warrants, (ii) vesting of RSUs and RSAs, and (iii) the purchase from contributions to the 2012 Employee Stock Purchase Plan (the ESPP) (calculated based on the treasury stock method), are only included in the calculation of diluted net loss per share when their effect is dilutive. The following potentially dilutive securities were excluded from the calculation of diluted net loss per share due to their anti-dilutive effect (in thousands): Year Ended December 31, 2020 2019 2018 Options to purchase common stock, including purchases from contributions to ESPP 7,118 9,304 10,731 Restricted stock units 406 369 440 Restricted stock awards 14 31 27 Warrants to purchase common stock (1) 150 150 150 7,688 9,854 11,348 (1) In 2012, the Company issued a warrant with a ten-year Recent Accounting Pronouncements In June 2016, the Financial Accounting Standard Board ( Financial Instruments – Credit Losses: Measurement of Credit Losses on Financial Instruments The Company has reviewed other recent accounting pronouncements and concluded they are either not applicable to the business or that no material effect is expected on the consolidated financial statements as a result of future adoption.

Cash Equivalents, Restricted Ca

Cash Equivalents, Restricted Cash and Investments	12 Months Ended
	Dec. 31, 2020
Investments Debt And Equity Securities [Abstract]
Cash Equivalents, Restricted Cash and Investments	3. Cash Equivalents, Restricted Cash and Investments Cash, Cash Equivalents and Restricted Cash The following table provides a reconciliation of cash, cash equivalents and restricted cash shown in the Consolidated Statements of Cash Flows (in thousands): December 31, 2020 2019 Cash and cash equivalents $ 32,297 $ 39,179 Restricted cash included in Other assets 1,080 1,080 Total cash, cash equivalents and restricted cash $ 33,377 $ 40,259 Restricted cash as of December 31, 2020 and 2019 was held as collateral for a stand-by letter of credit issued by the Company to its landlord in connection with the lease of the Company’s facility in San Carlos, California. See “Note 8. Commitments” for additional information on this lease. Cash Equivalents and Investments The amortized cost and fair value of cash equivalents and investments at December 31, 2020 and 2019 were as follows (in thousands): December 31, 2020 Amortized Gross Unrealized Fair Cost Gains Losses Value Money market fund $ 30,139 $ — $ — $ 30,139 U.S. treasury securities 176,625 60 — 176,685 Government-sponsored agencies 12,500 — — 12,500 Commercial paper 140,364 — — 140,364 Asset-backed securities 25,706 23 — 25,729 Corporate debt securities 72,764 38 (7 ) 72,795 Total available-for-sale securities $ 458,098 $ 121 $ (7 ) $ 458,212 Classified as: Cash equivalents $ 30,139 Short-term investments 404,273 Long-term investments 23,800 Total available-for-sale securities $ 458,212 3. Cash Equivalents, Restricted Cash and Investments (continued) December 31, 2019 Amortized Gross Unrealized Fair Cost Gains Losses Value Money market fund $ 30,353 $ — $ — $ 30,353 U.S. treasury securities 40,245 47 — 40,292 Commercial paper 12,429 — — 12,429 Asset-backed securities 25,436 50 — 25,486 Corporate debt securities 84,605 225 (4 ) 84,826 Total available-for-sale securities $ 193,068 $ 322 $ (4 ) $ 193,386 Classified as: Cash equivalents $ 30,325 Short-term investments 133,607 Long-term investments 29,454 Total available-for-sale securities $ 193,386 Cash equivalents in the tables above exclude cash of $2.2 million and $8.9 million as of December 31, 2020 and 2019, respectively. All available-for-sale securities held as of December 31, 2020 had contractual maturities of less than two years. There have been no significant realized gains or losses on available-for-sale securities for the periods presented. The Company applies the specific identification method to determine the cost basis of the securities sold. No available-for-sale securities held as of December 31, 2020 have been in a continuous unrealized loss position for more than 12 months. As of December 31, 2020, unrealized losses on available-for-sale investments are not attributed to credit risk. The Company believes that it is more-likely-than-not that investments in an unrealized loss position will be held until maturity or the recovery of the cost basis of the investment. The Company believes that an allowance for credit losses is unnecessary because the unrealized losses on certain of the Company’s marketable securities are due to market factors

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	4. The Company determines the fair value of financial assets and liabilities using three levels of inputs as follows: Level 1—Inputs which include quoted prices in active markets for identical assets and liabilities. Level 2—Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. 4. Recurring Fair Value Measurements The Company’s financial assets subject to fair value measurements on a recurring basis and the level of inputs used in such measurements were as follows as of December 31, 2020 and 2019 (in thousands): December 31, 2020 Description Level 1 Level 2 Level 3 Total Money market fund $ 30,139 $ — $ — $ 30,139 U.S. treasury securities — 176,685 — 176,685 Government-sponsored agencies — 12,500 — 12,500 Commercial paper — 140,364 — 140,364 Asset-backed securities — 25,729 — 25,729 Corporate debt securities — 72,795 — 72,795 Total assets $ 30,139 $ 428,073 $ — $ 458,212 December 31, 2019 Description Level 1 Level 2 Level 3 Total Money market fund $ 30,353 $ — $ — $ 30,353 U.S. treasury securities — 40,292 — 40,292 Commercial paper — 12,429 — 12,429 Asset-backed securities — 25,486 — 25,486 Corporate debt securities — 84,826 — 84,826 Total assets $ 30,353 $ 163,033 $ — $ 193,386 During the year ended December 31, 2020 there were no transfers between Level 1 and Level 2 financial assets. When the Company uses observable market prices for identical securities that are traded in less active markets, the Company classifies its marketable debt instruments as Level 2. When observable market prices for identical securities are not available, the Company prices its marketable debt instruments using non-binding market consensus prices that are corroborated with observable market data; quoted market prices for similar instruments; or pricing models, such as a discounted cash flow model, with all significant inputs derived from or corroborated with observable market data. Non-binding market consensus prices are based on the proprietary valuation models of pricing providers or brokers. These valuation models incorporate a number of inputs, including non-binding and binding broker quotes; observable market prices for identical or similar securities; and the internal assumptions of pricing providers or brokers that use observable market inputs and, to a lesser degree, unobservable market inputs. The Company corroborates non-binding market consensus prices with observable market data using statistical models when observable market data exists. The discounted cash flow model uses observable market inputs, such as LIBOR-based yield curves, currency spot and forward rates, and credit ratings. Other Fair Value Measurements The carrying amount and estimated fair value of financial instruments not recorded at fair value at December 31, 2020 and 2019 were as follows (in thousands): December 31, December 31, 2020 2019 Carrying Amount Estimated Fair Value Carrying Amount Estimated Fair Value Long-term debt, net (1) $ 24,401 $ 25,332 $ 19,786 $ 20,253 (1) Carrying amounts of long-term debt were net of unamortized debt discounts of $599 and $214 as of December 31, 2020 and 2019, respectively. 4. The fair value of the Company's long-term debt is estimated using the net present value of future debt payments, discounted at an interest rate that is consistent with market interest rates, which is a Level 2 input.

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2020
Property Plant And Equipment [Abstract]
Property and Equipment	5. Property and Equipment Property and equipment consist of the following (in thousands): December 31, 2020 2019 Lab equipment $ 6,098 $ 6,747 Computer equipment and software 738 1,865 Furniture and fixtures 381 552 Tenant improvements 24,826 1,607 32,043 10,771 Less: accumulated depreciation (6,883 ) (8,617 ) $ 25,160 $ 2,154

Accrued and Other Current Liabi

Accrued and Other Current Liabilities	12 Months Ended
	Dec. 31, 2020
Payables And Accruals [Abstract]
Accrued and Other Current Liabilities	6. Accrued and other current liabilities consist of the following (in thousands): December 31, 2020 2019 Research and development related $ 11,062 $ 13,100 Compensation related 5,498 3,608 Consulting and professional services 1,690 1,094 Current portion of operating lease liability 845 1,503 Other 699 501 $ 19,794 $ 19,806

Long-term Debt

Long-term Debt	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Long-term Debt	7. Long-term Debt In December 2017, the Company entered into a Loan and Security Agreement with Hercules Capital, Inc. (Hercules), pursuant to which term loans in an aggregate principal amount of up to $50.0 million (as amended, the Credit Facility) were available to the Company. As of December 31, 2020, the Company had borrowed $20.0 million under the Credit Facility, with an interest rate of 8.05% per annum, and the remaining available amount had expired. Advances under the Credit Facility bear an interest rate equal to the greater of either (i) 8.05% plus the prime rate as reported from time to time in The Wall Street Journal (the Prime Rate) minus 4.75%, and (ii) 8.05%. The Company will make interest-only payments through July 1, 2021, and will then repay the principal balance and interest on the advances in equal monthly installments continuing through December 1, 2022. The Company will pay an end of term charge of $1.3 million in December 2022. 7. Long-term Debt (continued) On January 8, 2020, the Company entered into an Amended and Restated Loan and Security Agreement (the Amended Loan Agreement) with Hercules, which amended and restated the agreement between the parties, and pursuant to which an additional term loan in an aggregate principal amount of up to $100.0 million (the Restated Credit Facility) is available to the Company at its discretion in three tranches. The first tranche of the Restated Credit Facility of up to $40.0 million was available to the Company through December 15, 2020, of which $20.0 million became available upon submission of the avacopan New Drug Application (NDA) for the treatment of patients with anti-neutrophil cytoplasmic auto-antibody associated vasculitis (ANCA vasculitis). The second tranche of up to an additional $30.0 million would be available to the Company through December 15, 2021 upon NDA approval of avacopan for the treatment of ANCA vasculitis. The third tranche of up to an additional $30.0 million would be available through December 15, 2022, subject to certain conditions. Under the Restated Credit Facility, the Company borrowed $5.0 million from the first tranche with an interest rate of 8.50% per annum as of December 31, 2020. Advances under the Restated Credit Facility bear an initial interest rate equal to the greater of either (i) 8.50% plus the Prime Rate minus 5.25%, and (ii) 8.50%, which may be reduced upon the Company achieving certain cumulative net avacopan revenue levels. For advances under the Restated Credit Facility, the Company will make interest only payments through September 1, 2022 and will then repay the principal balance and interest on the advances in equal monthly installments through February 1, 2024. Upon satisfaction of certain conditions, the interest-only payment period and the principal balance repayment period may be extended. In addition, the Company will pay an end of term charge of 7.15% of the aggregate amount of the advances under the Restated Credit Facility. The Company paid a commitment fee of 1% of the advances made by Hercules, with a minimum charge of $162,500 for the Credit Facility and a minimum charge of $520,000 for the Also, the Company reimbursed Hercules for costs incurred related to the . These charges were recorded as discounts to the carrying value of the loan and are amortized over the term of the loan using the effective interest method. In addition, the Company may prepay advances under the Restated Credit Facility, in whole or in part, at any time, subject to a prepayment charge that ranges from 1.0% to 2.0%, depending on the timing of the prepayment. The Restated Credit Facility is secured by substantially all of the Company’s assets, excluding intellectual property. The Restated Credit Facility also includes customary loan covenants, with which the Company was in compliance for all periods presented. In connection with the Restated Credit Facility, the Company also entered into a Right to Invest Agreement with Hercules, pursuant to which Hercules shall have the right to participate, in an amount up to $3.0 million, in any subsequent equity financing broadly marketed to multiple investors in an amount greater than $30.0 million. 7. Long-term Debt (continued) As of December 31, 2020, the Company had outstanding borrowings under the Amended Loan Agreement of $24.4 million, net of discounts of $0.6 million. Future minimum principal payments, which exclude the end of term charge, as of December 31, 2020 are as follows (in thousands): Amounts Year ending December 31: 2021 $ 6,389 2022 14,666 2023 3,353 2024 592 Total minimum payments 25,000 Less: amount representing debt discount (599 ) Present value of remaining debt payments 24,401 Less: current portion (6,302 ) Non-current portion $ 18,099

Commitments

Commitments	12 Months Ended
	Dec. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Commitments	8. Commitments Operating Leases In May 2004, the Company entered into a noncancelable operating lease for its current office and primary research facility located in Mountain View, California. In May 2019, the Company entered into a third amendment to the lease agreement for the same facility to extend the term of the lease through April 2021. In July 2020, the Company entered into a letter agreement to further extend the lease term through June 2021. In July 2019, the Company entered into a ten-year The Company was provided a tenant improvement allowance of $15.4 million plus an additional allowance of $4.8 million for the same. The additional allowance will be repaid by the Company as additional rent in equal monthly payments at a rate of 7% per annum through the initial term of the lease. As of December 31, 2020, the Company received a tenant improvement allowance of $9.3 million. The Company has the right to sublease the facility, subject to landlord consent. 8. Commitments (continued) The balance sheet classification of the Company’s operating lease assets and liabilities was as follows (in thousands): December 31, 2020 2019 Balance Sheet Assets: Operating lease right-of-use assets $ 26,911 $ 1,704 Liabilities: Operating lease liabilities: Accrued and other current liabilities (1) $ 845 $ 1,503 Non-current lease liabilities 38,671 566 (1) Includes current portion of operating lease liabilities. The component of lease costs, which was included in operating expenses in the Company’s Consolidated Statements of Operations, was as follows (in thousands): Year Ended December 31, 2020 2019 2018 Operating lease cost $ 4,648 $ 1,295 $ 1,072 For the years ended December 31, 2020 and 2019, cash paid for amounts included in the measurement of lease liabilities was $1.7 million, excluding the $9.3 million tenant improvement allowance received, and $1.3 million, respectively. These amounts were included in net cash used in operating activities in the Company’s Consolidated Statements of Cash Flows. Future minimum lease payments under all noncancelable operating leases as of December 31, 2020, are as follows (in thousands): Operating leases Year ending December 31: 2021 $ 5,210 2022 7,316 2023 7,516 2024 7,721 2025 7,932 Thereafter 44,585 Total minimum payments 80,280 Less: interest (30,296 ) Less: future tenant improvement reimbursements (10,468 ) Present value of lease liabilities $ 39,516 As of December 31, 2020, the weighted-average remaining lease term was 10.0 years and the weighted-average operating discount rate used to determine the operating lease liability was 9.5%.

Related-Party Transactions

Related-Party Transactions	12 Months Ended
	Dec. 31, 2020
Related Party Transactions [Abstract]
Related-Party Transactions	9. Related Party Transactions Vifor Vifor held Avacopan Agreements In May 2016, the Company entered into an exclusive collaboration and license agreement with Vifor pursuant to which the Company granted Vifor exclusive rights to commercialize avacopan in Europe and certain other markets (the Avacopan Agreement). Avacopan is the Company’s lead drug candidate for the treatment of patients with ANCA vasculitis In February 2017, Vifor and the Company expanded the Vifor territories under the Avacopan Agreement to include all markets outside the United States and China (the Avacopan Amendment). In connection with this February 2017 amendment, the Company received a $20.0 million upfront payment for the expanded rights. In June 2018, Vifor and the Company further expanded the Vifor territories under the Avacopan Agreement to provide Vifor with exclusive commercialization rights in China (the Avacopan Letter Agreement, and together with the Avacopan Agreement and the Avacopan Amendment, the Avacopan Agreements). The Company retains control of ongoing and future development of avacopan (other than country-specific development in the licensed territories) and all commercialization rights to avacopan in the United States. In consideration for the Avacopan Letter Agreement, the Company received a $5.0 million payment for the expanded rights. Upon achievement of certain regulatory and commercial milestones with avacopan, the Company will receive additional payments of up to $460.0 million under the Avacopan Agreements. In addition, the Company will receive royalties, with rates ranging from the low teens to the mid-twenties, on future potential net sales of avacopan by Vifor in the licensed territories. In December 2017, the Company achieved a $50.0 million regulatory milestone when the European Medicines Agency (EMA) validated the Company’s conditional marketing authorization (CMA) application for avacopan for the treatment of ANCA vasculitis. The Company identified the following material promises under the Avacopan Agreements: (1) the license related to avacopan; (2) the development and regulatory services for the submission of the marketing authorization application (MAA); and (3) an exclusive option to negotiate a worldwide license agreement for CCX140, which expired in 2016. 9. Related Party Transactions (continued) As of December 31, 2020, the transaction price of $153.0 million comprises the following: • $78.0 million upfront payment under the May 2016 Avacopan Agreement. Of the total $85.0 million upfront payment received under the May 2016 Avacopan Agreement, $7.0 million was allocated to the issuance of 3,333,333 shares of the Company’s common stock valued at $2.10 per share, the closing stock • $20.0 million upfront payment under the February 2017 Avacopan Amendment; • $50.0 million regulatory milestone payment achieved upon the validation of the Company’s CMA application by the EMA, for avacopan for the treatment of ANCA vasculitis in December 2017; and • $5.0 million non-refundable upfront payment under the Avacopan Letter Agreement The Company will re-evaluate the transaction price in each reporting period and as uncertain events are resolved or other changes in circumstances occur. The Company determined that the combined performance obligation will be performed over the duration of the contract, which began on the effective date of May 9, 2016 and ends upon completion of development and regulatory services. The Company uses a cost-based input method to measure proportional performance and to calculate the corresponding amount of revenue to recognize. The Company believes this is the best measure of progress because other measures do not reflect how the Company transfers its performance obligation to Vifor. In applying the cost-based input method of revenue recognition, the Company measures actual costs incurred relative to budgeted costs to fulfill the combined performance obligation. These costs consist primarily of third-party contract costs. Revenue is recognized based on actual costs incurred as a percentage of total budgeted costs as the Company completes its performance obligations. Avacopan Commercial Supply Agreement In October 2020, the Company entered into a Manufacturing and Supply Agreement with Vifor (the Avacopan Commercial Supply Agreement). Under the Avacopan Commercial Supply Agreement, the Company will supply and sell avacopan drug product to Vifor for commercial use outside of the United States. Vifor will purchase avacopan drug product at a certain percentage mark up to the Company’s cost of goods, in accordance with the Avacopan Agreements. Vifor’s purchase of avacopan drug product is subject to certain binding forecast periods. The Avacopan Commercial Supply Agreement will expire upon the termination of the Avacopan Agreements or under certain circumstances as specified in the agreement. In connection with the Avacopan Commercial Supply Agreement, the Company also entered into a letter agreement with Vifor, pursuant to which the $6.2 million previously received from Vifor under the CCX140 Agreement (discussed below) is creditable to Vifor’s purchase of avacopan drug product. No revenue was recognized during the year ended December 31, 2020 under the Avacopan Commercial Supply Agreement. For the years ended December 31, 2020, 2019 and 2018, the Company recognized $13.0 million CCX140 Agreements In December 2016, the Company entered into a second collaboration and license agreement with Vifor pursuant to which the Company granted Vifor exclusive rights to commercialize CCX140 (the CCX140 Agreement) in markets outside the United States and China. CCX140 is an orally-administered inhibitor of the chemokine receptor known as CCR2. The Company retains marketing rights in the United States and China, while Vifor has commercialization rights in the rest of the world. Pursuant to the CCX140 Agreement, the Company is responsible for the clinical development of CCX140 in rare renal diseases and is reimbursed for Vifor’s equal share of such development cost. Under the terms of the CCX140 Agreement, the Company received a non-refundable upfront payment of $50.0 million in 2017. 9. Related Party Transactions (continued) In June 2018, the Company and Vifor entered into a letter agreement to expand Vifor’s rights to include the right to exclusively commercialize CCX140 in China (the CCX140 Letter Agreement). In connection with the CCX140 Letter Agreement, the Company received a non-refundable payment of $5.0 million. The Company and Vifor also entered into an amendment to the CCX140 Agreement (the CCX140 Amendment, and together with the CCX140 Agreement and the CCX140 Letter Agreement, the CCX140 Agreements) to clarify the timing of certain payments with respect to development funding of the CCX140 program by Vifor, and the Company received a non-refundable payment of $11.5 million. The Company retains control of ongoing and future development of CCX140 (other than country-specific development in the licensed territories), and all commercialization rights to CCX140 in the United States. The Company identified the following material promises under the CCX140 Agreements: (1) the license related to CCX140; and (2) the development and regulatory services for the submission of the MAA. The Company considered that the license has standalone functionality and is capable of being distinct. However, the Company determined that the license is not distinct from the development and regulatory services within the context of the agreement because Vifor is dependent on the Company to execute the development and regulatory activities in order for Vifor to benefit from the license. As such, the license is combined with the development and regulatory services into a single performance obligation. As of December 31, 2020, the transaction price of $66.5 million comprises the following: • $50.0 million upfront payment under the CCX140 Agreement; • $11.5 million of CCX140 development funding by Vifor; and • $5.0 million non-refundable upfront payment under the CCX140 Letter Agreement. The Company determined that the combined performance obligation will be performed over the duration of the contract, which began on the effective date of December 22, 2016 and ends upon completion of development services. The Company uses a cost-based input method to measure proportional performance and to calculate the corresponding amount of revenue to recognize. The Company believes this is the best measure of progress because other measures do not reflect how the Company transfers its performance obligation to Vifor. In applying the cost-based input method of revenue recognition, the Company measures actual costs incurred relative to budgeted costs to fulfill the combined performance obligation. These costs consist primarily of third-party contract costs. Revenue is recognized based on actual costs incurred as a percentage of total budgeted costs as the Company completes its performance obligations. In May 2020, the Company announced topline data from a 46 patient Phase II dose-ranging trial in the orphan kidney disorder, primary Focal Segmental Glomerulosclerosis (FSGS), called the LUMINA-1 trial. In the study, CCX140 did not demonstrate a meaningful reduction in proteinuria relative to the control group after 12 weeks of blinded treatment. As such, CCX140 will not be further developed in FSGS. As a result, the Company reduced the total anticipated FSGS budgeted costs and the corresponding transaction price related to development funding under the CCX140 Agreement by $47.2 million and recognized $46.7 million of contract revenue during the three months ended June 30, 2020. In addition, $6.2 million of deferred revenue previously received from Vifor under the CCX140 Agreements is creditable against Vifor’s purchases of avacopan drug product under the Avacopan Commercial Supply Agreement. Vifor retains an option to solely develop and commercialize CCX140 in more prevalent forms of chronic kidney disease (CKD). Should Vifor later exercise the CKD option, the Company would receive co-promotion rights for CKD in the United States. For the years ended December 31, 2020, 2019 and 2018, the Company recognized $51.4 million, $6.4 million and $5.8 million of collaboration and license revenue under the CCX140 Agreements, respectively. As of December 31, 2020, 9. Related Party Transactions (continued) The following table presents the contract assets and liabilities for all of the Company’s revenue contracts as of the following dates (in thousands): December 31, 2020 2019 Contract asset: Accounts receivable $ 32 $ — Contract liability: Deferred revenue (36,587 ) (100,837 ) During the years ended December 31, 2020, 2019 and 2018, the Company recognized the following revenue as a result of changes in the contract asset and the contract liability balances (in thousands): Year Ended December 31, 2020 2019 2018 Revenue recognized in the period from: Amount included in contract liability at the beginning of the period $ 64,250 $ 35,781 $ 39,815 Performance obligations satisfied (or partially satisfied) in previous periods $ (40,647 ) $ (2,251 ) $ (3,357 )

Government Grant

Government Grant	12 Months Ended
	Dec. 31, 2020
Government Grants [Abstract]
Government Grant	10. Government Grant In September 2019, the Company was awarded a two-year million grant from the orphan drug office of the U.S. Food and Drug

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stockholders' Equity	11. Stockholders’ Equity Equity Incentive Plans In May 2002, the stockholders approved the Amended and Restated 1997 Stock Option/Stock Issuance Plan (the 1997 Plan) and in September 2002, the stockholders approved the 2002 Equity Incentive Plan (the 2002 Plan). In February 2012, the stockholders approved the 2012 Equity Incentive Award Plan (the 2012 Plan). As of December 31, 2020, a total of 17,440,000 shares of the Company’s common stock were reserved for issuance under the 2012 Plan. In addition, the number of shares available for issuance under the 2012 Plan will be annually increased by an amount equal to the lesser of: 2,000,000 shares; 4% of the outstanding shares of the Company’s common stock as of the last day of the Company’s immediately preceding fiscal year; or an amount determined by the Company’s Board of Directors. In November 2020, the Board of Directors approved an increase to the number of shares reserved for issuance under the 2012 Plan by 2,000,000 shares effective January 1, 2021. Collectively, the 1997 Plan, the 2002 Plan and the 2012 Plan are known as the Stock Plans. 11. Stockholders’ Equity (continued) Restricted Stock Restricted Stock Awards (RSAs) and Restricted Stock Units (RSUs) are independent of stock option grants and are not transferrable, and are subject to forfeiture if recipients terminate their service to the Company prior to the release of the vesting restrictions. RSUs granted to employees generally vest over a period of three years. RSUs and RSAs granted to its nonemployee directors vest over a one-year period, or over a three-year period in the case of an initial grant pursuant to the Company’s Non-Employee Director Compensation Policy (Directors Plan). In the case of a change in control, RSUs and RSAs granted to nonemployee directors will vest in full. RSUs are also granted to nonemployee with performance conditions and the related compensation expense is recognized when the performance condition is deemed probable to be achieved. RSUs and RSAs are valued at the closing price of the Company’s common stock on the date of grant. During the years ended December 31, 2019 and 2018, the weighted-average grant date fair value for restricted stock granted was $11.54 and $11.32, respectively. The total fair value of restricted stock vested during the years ended December 31, 2020, 2019 and 2018 was $11.4 million, $3.1 million and $2.4 million, respectively. The activity for restricted stock is summarized as follows: Shares Weighted- Average Grant-Date Fair Value Balance at December 31, 2019 399,823 $ 10.54 Granted 280,360 49.26 Vested (248,486 ) 13.32 Canceled (11,667 ) 10.95 Unvested at December 31, 2020 420,030 $ 34.73 As of December 31, 2020, there was $6.4 million of unrecognized compensation expense associated with unvested employee restricted stock, Stock Options Under the Stock Plans, incentive stock options may be granted by the Board of Directors to employees at exercise prices of not less than 100% of the fair value at the date of grant. Nonstatutory options may be granted by the Board of Directors to employees, officers, and directors of the Company or consultants at exercise prices of not less than 85% of the fair value of the common stock on the date of grant. The fair value at the date of grant is determined by the Board of Directors. Under the Stock Plans, options may be granted with different vesting terms from time to time, but not to exceed 10 years from the date of grant. Outstanding options generally vest over four years, with 25% of the total grant vesting on the first anniversary of the option grant date and 1/36 11. Stockholders’ Equity (continued) The following table summarizes stock option activity and related information under the Company’s Stock Plans: Available for Grant Share s Weighted Average Exercise Price Weighted Average Remaining Contractual Term (in years) Aggregate Intrinsic Value Balance at December 31, 2019 2,192,545 9,287,901 $ 9.44 Shares authorized 2,000,000 — Granted (1) (1,267,668 ) 987,308 49.52 Exercised (2) 92,459 (3,019,410 ) 9.70 Forfeited and expired (3) 153,241 (141,574 ) 23.97 Outstanding at December 31, 2020 3,170,577 7,114,225 $ 14.61 6.53 $ 336,617,882 Vested and expected to vest, net of estimated forfeiture at December 31, 2020 6,886,096 $ 14.16 6.46 $ 328,929,110 Exercisable at December 31, 2020 4,491,790 $ 8.52 5.42 $ 239,880,734 (1) The difference between shares granted in the number of shares available for grant and outstanding options represents the RSUs and RSAs granted for the period. (2) Shares presented as available for grant represents shares repurchased for tax withholding upon vesting of RSUs. (3) The difference between shares forfeited and expired in the number of shares available for grant and outstanding options represents the RSUs canceled during the period. The aggregate intrinsic value represents the value of the Company’s closing stock price on the last trading day of the period in excess of the weighted-average exercise price multiplied by the number of options outstanding or exercisable. Total intrinsic value of options exercised was $123.3 million, $48.4 million and $9.8 million during 2020, 2019 and 2018, respectively. As of December 31, 2020, there was $33.8 million of unrecognized compensation expense, net of estimated forfeitures, associated with outstanding employee stock options, which is expected to be recognized over an estimated weighted-average period of 2.3 years. As of December 31, 2020, stock options outstanding were as follows: Options Outstanding Exercise Price Range Shares Weighted- Average Contractual Life $3.29 - $5.95 711,839 5.38 $6.08 - $6.62 963,248 5.48 $6.66 - $8.19 1,267,114 4.45 $8.29 - $10.82 331,926 7.45 $10.86 733,395 7.17 $10.91 - $10.93 27,492 7.64 $11.02 955,222 8.12 $11.56 - $13.89 764,764 7.75 $13.94 - $46.52 847,357 6.19 $46.59 - $62.39 511,868 9.43 7,114,225 6.53 11. Stockholders’ Equity (continued) Employee Stock Purchase Plan In February 2012, the stockholders approved the ESPP. As of December 31, 2020, a total of 1,700,000 shares of the Company’s common stock were reserved for issuance under the ESPP. In addition, the number of shares available for issuance under the ESPP may be annually increased on the first day of each fiscal year during the term of the ESPP, beginning with the 2012 fiscal year, by an amount equal to the lesser of: 300,000 shares; 1% of outstanding shares of the Company’s common stock; or an amount determined by the Company’s Board of Directors. The ESPP provides for an aggregate limit of 3,000,000 shares of common stock that may be issued under the ESPP during the term of the ESPP. In November 2020, the Board of Directors approved an increase to the number of shares reserved for issuance under the ESPP by 300,000 shares effective January 1, 2021. The Company issued 79,161, 71,653 and 88,784 shares under the ESPP in 2020, 2019 and 2018, respectively. As of December 31, 2020, 843,737 shares were available for issuance under the ESPP. As of December 31, 2020, there was $0.2 million of unrecognized compensation expense, net of estimated forfeitures, associated with the ESPP, which is expected to be recognized over an estimated weighted-average period of 0.4 years. Stock Awards Granted to Employees Employee stock-based compensation expense recognized is calculated based on awards ultimately expected to vest and reduced for estimated forfeitures. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. Total employee stock-based compensation expense recognized associated with restricted stock, stock options, and the ESPP, was as follows (in thousands): Year Ended December 31, 2020 2019 2018 Research and development $ 7,815 $ 4,530 $ 3,632 General and administrative 13,133 6,819 6,339 Total $ 20,948 $ 11,349 $ 9,971 Valuation Assumptions Fair value of options granted under the Stock Plans and purchases under the Company’s ESPP were estimated at grant or purchase dates using a Black-Scholes option valuation model. The Black-Scholes valuation model requires that assumptions are made with respect to various factors, including the expected volatility of the fair value of the Company’s common stock. The Company has based its expected volatility on the average historical volatilities of public entities having similar characteristics including: industry, stage of life cycle, size, and financial leverage. The weighted-average expected term of options was calculated using the simplified method as prescribed by accounting guidance for stock-based compensation. This decision was based on the lack of relevant historical data due to the Company’s limited historical experience. 11. Stockholders’ Equity (continued) The fair values of the employee stock options granted under the Company’s Stock Plans and the option component of the shares purchased under the ESPP during 2020, 2019 and 2018 were estimated at the date of grant using the Black-Scholes option-pricing model with the following assumptions: Employee Stock Options Employee Stock Purchase Plan 2020 2019 2018 2020 2019 2018 Dividend yield 0 % 0 % 0 % 0 % 0 % 0 % Volatility 87.4 % 71.3 % 67.8 % 118.4 % 56.4 % 73.8 % Weighted-average expected life (in years) 6.0 6.0 6.0 0.5 0.5 0.5 Risk-free interest rate 0.66 % 2.28 % 2.66 % 0.13 % 1.87 % 2.33 % Weighted-average grant date fair value $ 35.71 $ 7.54 $ 6.22 $ 25.93 $ 4.10 $ 3.73 Stock Awards to Nonemployees During 2020, 2019 and 2018, the Company granted to consultants options to purchase 21,400, 82,011 and 28,534 shares of common stock, respectively. In addition, during 2020, 66,000 shares of RSUs were granted to consultants, of which 35,000 were with performance vesting conditions. Total stock-based compensation expense recognized associated with restricted stock and stock options granted to nonemployees was as follows (in thousands): Year Ended December 31, 2020 2019 2018 Research and development $ 1,892 $ 186 $ 862 General and administrative 72 103 — Total $ 1,964 $ 289 $ 862 Valuation Assumptions Stock-based compensation expense associated with stock options granted to nonemployees is recognized as the stock options vest. The estimated fair values of the stock options granted are calculated at each reporting date using the Black-Scholes option-pricing model, with the following assumptions: Year Ended December 31, 2020 2019 2018 Dividend yield 0% 0% 0% Volatility 87% 68-87% 67-68% Weighted-average expected life (in years) 6.0 5.5-6.0 5.7-9.9 Risk-free interest rate 0.84% 1.6-2.2% 2.7-3.0% Equity Distribution Agreement In December 2018, the Company entered into an Equity Distribution Agreement (EDA), pursuant to which the Company may offer and sell, from time to time, shares of the Company’s common stock, par value $0.001 per share, having an aggregate offering price of up to $75.0 million. For the year ended December 31, 2019, the Company sold 6,491,196 shares of its common stock pursuant to its EDA for net proceeds of $73.3 million. These sales fully exhausted the amount available under the EDA. Accordingly, no further sales will be made under the EDA. 11. Stockholders’ Equity (continued) Equity Follow-On Offering In June 2020, the Company completed an equity follow-on offering of 5,980,000 shares of its common stock at a public offering price of $58.00 per share. The Company received net proceeds of approximately $325.7 million, after deducting underwriting discounts, commissions and offering expenses.

401(k) Plan

401(k) Plan	12 Months Ended
	Dec. 31, 2020
Postemployment Benefits [Abstract]
401(k) Plan	12. 401(k) Plan In October 1997, the Company established the ChemoCentryx 401(k) Plan and Trust (the 401(k) Plan). Employees may contribute, up to the percentage limit imposed by the Internal Revenue Code of 1986, as amended, an amount of their salary each calendar year until termination of their employment with the Company. The Company may elect to make matching contributions, as per the Plan; however, no matching contributions were made in the years ended December 31, 2020, 2019 and 2018.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	13. Income Taxes The Company’s loss before tax is only attributable to U.S. operations. The components of the income tax (benefit) expense are as follows (in thousands): Year Ended December 31, 2020 2019 2018 Current (benefit from) provision for income taxes: Federal $ — $ — $ — State — — — Total current (benefit from) provision for income taxes — — — Deferred (benefit from) provision for income taxes: — — — Federal — — — State — — — Total deferred tax (benefit from) provision for income taxes — — — (Benefit from) provision for income taxes $ — $ — $ — A reconciliation of the federal statutory income tax rate to the Company’s effective income tax rate is as follows: Year Ended December 31, 2020 2019 2018 Federal statutory income tax rate (21.0 %) (21.0 %) (21.0 %) Permanent items 2.1 1.3 1.6 Excess tax benefit for stock-based compensation (40.9 ) (13.3 ) (2.8 ) Tax credits (13.4 ) (38.3 ) (3.5 ) Change in valuation allowance 70.4 70.3 24.5 Non-deductible executive compensation 2.7 1.0 0.6 Other 0.1 — 0.6 (Benefit from) provision for income taxes — % — % — % 13. Income Taxes (continued) The tax effects of temporary differences and carryforwards that give rise to significant portions of the deferred tax assets consist of the following (in thousands): December 31, 2020 2019 Deferred tax assets: Net operating loss carryforwards $ 120,347 $ 76,033 Tax credits 49,229 39,625 Amortization of deferred stock compensation - non- qualified 4,165 5,172 Reserves and accruals 1,770 1,528 Deferred revenue 7,684 20,312 Depreciation and amortization — 15 Lease liability 8,299 434 Gross deferred tax assets 191,494 143,119 Less: valuation allowance (183,948 ) (142,761 ) Total deferred tax assets 7,546 358 Deferred tax liabilities: Property, Plant and Equipment (1,894 ) — Right of use asset (5,652 ) (358 ) Total deferred tax liabilities (7,546 ) (358 ) Net deferred tax assets $ — $ — The Company concluded that it is more likely than not that its deferred tax assets would not be realized. Accordingly, the total deferred tax assets have been fully offset by a valuation allowance. The Company’s valuation allowance increased by approximately $41.2 million and $39.9 million in 2020 and 2019, respectively. At December 31, 2020, the Company had federal and state net operating loss carryforwards of approximately $489.7 million and $225.7 million, respectively. The federal net operating loss carryforwards will begin to expire in 2032. Due to tax reform, federal net operating loss carryforwards generated in 2018 and forward no longer have an expiration date. The state net operating loss carryforwards will begin to expire in 2028. As of December 31, 2020, the Company has federal and state research and development credit carryforwards of $14.2 million and $12.2 million, respectively. The federal research and development credits will begin to expire in 2021 if not utilized. California research and development credits can be carried forward indefinitely. The Company also has federal Orphan Drug credits of $52.6 million as of December 31, 2020. Such orphan drug credit will begin to expire in 2034 if not utilized. Utilization of the net operating loss and credit carryforwards may be subject to annual limitation due to historical or future ownership percentage change rules provided by the Internal Revenue Code of 1986, and similar state provisions. The annual limitation may result in the expiration of certain net operating loss and credit carryforwards before their utilization. 13. Income Taxes (continued) A reconciliation of the Company’s unrecognized tax benefits for the years ended December 31, 2020, 2019 and 2018, is as follows (in thousands): Unrecognized Income Tax Benefits Balance as of December 31, 2018 $ 9,714 Additions for current tax positions 3,455 Additions for prior tax positions 16,007 Balance as of December 31, 2019 29,176 Additions for current tax positions 1,317 Releases (29 ) Balance as of December 31, 2020 $ 30,464 As of December 31, 2020 and 2019, the Company had approximately $30.5 million and $29.2 million, respectively, of unrecognized tax benefits, none of which would currently affect the Company’s effective tax rate if recognized due to the Company’s deferred tax assets being fully offset by a valuation allowance. In 2020, unrecognized tax benefits increased due to uncertainty associated with the Company’s claim of 2020 federal and California research and development and orphan drug credits. In 2020, unrecognized tax benefits decreased due to expiration of federal research and development credit. The Company is not aware of any items that will significantly increase or decrease its unrecognized tax benefits in the next 12 months. If applicable, the Company would classify interest and penalties related to uncertain tax positions in income tax expense. Through December 31, 2020, there has been no interest expense or penalties related to unrecognized tax benefits. For U.S. federal and California income tax purposes, the statute of limitations remains open for the years beginning 2017 and 2016, respectively, except for the carryforward of net operating losses and research and development credits generated in prior years.

Selected Quarterly Financial Da

Selected Quarterly Financial Data	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data	14. Selected Quarterly Financial Data (unaudited) Selected quarterly results from operations for the years ended December 31, 2020 and 2019 are as follows (in thousands except per share amounts): 2020 Quarter Ended March 31 June 30 September 30 December 31 Revenue $ 6,008 $ 49,440 $ 5,085 $ 4,358 Net income (loss) $ (21,687 ) $ 20,267 $ (24,060 ) $ (29,876 ) Basic net income (loss) per share $ (0.35 ) $ 0.32 $ (0.35 ) $ (0.43 ) Diluted net income (loss) per share $ (0.35 ) $ 0.29 $ (0.35 ) $ (0.43 ) 2019 Quarter Ended March 31 June 30 September 30 December 31 Revenue $ 8,327 $ 7,173 $ 10,581 $ 10,047 Net loss $ (11,949 ) $ (15,150 ) $ (12,862 ) $ (15,528 ) Basic and diluted net loss per share $ (0.23 ) $ (0.26 ) $ (0.22 ) $ (0.26 ) The four quarters of net earnings per share may not add to the total year because of differences in the weighted-average numbers of shares outstanding during the quarters and the year.

Subsequent Event

Subsequent Event	12 Months Ended
	Dec. 31, 2020
Subsequent Events [Abstract]
Subsequent Event	15. Subsequent Event In February 2021, Vifor, through its Japanese sublicensee Kissei Pharmaceutical, Co., Ltd., filed the Japanese NDA (JNDA) for avacopan in the treatment of ANCA vasculitis with the Japanese Pharmaceuticals and Medical Device Agency. The acceptance of the JNDA resulted in the Company’s achievement of a $10.0 million regulatory milestone from Vifor.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The consolidated financial statements are prepared in conformity with accounting principles generally accepted in the United States (GAAP). The consolidated financial statements include the Company’s accounts and those of its wholly owned subsidiaries, ChemoCentryx Ireland Limited and ChemoCentryx Limited. The operations of ChemoCentryx Ireland Limited and ChemoCentryx Limited have been immaterial to date. All intercompany amounts have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from these estimates.
Cash Equivalents and Investments	Cash Equivalents and Investments The Company considers all highly liquid investments with an original maturity at the date of purchase of three months or less to be cash equivalents. The Company limits its concentration of risk by diversifying its investments among a variety of issuers. All investments are classified as available for sale and are recorded at fair value based on quoted prices in active markets or based upon other observable inputs, with unrealized gains and losses excluded from earnings and reported in other comprehensive income (loss). Purchase premiums and discounts are recognized in interest income using the interest method over the terms of the securities. Realized gains and losses and unrealized declines in fair value that are attributed to credit-related factors are reflected in the statement of operations. The cost of securities sold is based on the specific-identification method.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The carrying amounts of certain of the Company’s financial instruments, including cash and cash equivalents, short-term investments, accounts receivable and accounts payable, approximate their fair value due to their short maturities.
Concentration of Credit Risk	Concentration of Credit Risk The Company invests in a variety of financial instruments and, by its policy, limits the amount of credit exposure with any one issuer, industry or geographic area. For the years ended December 31, 2020, 2019 and 2018, 99.2%%, 99.5% and 100%, respectively, of the Company’s total revenue was derived from the Company’s collaboration with Vifor (International) Ltd., and/or its affiliates, or collectively, Vifor.
Property and Equipment	Property and Equipment Property and equipment are stated at cost less accumulated depreciation. Depreciation is calculated using the straight-line method over the estimated useful lives of the assets, which range from five to seven years. Tenant improvements are depreciated over the lesser of the estimated useful life or the remaining life of the lease at the time the asset is placed into service.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets The Company reviews long-lived assets, including property and equipment, for impairment whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. An impairment loss would be recognized when estimated undiscounted future cash flows expected to result from the use of an asset are less than its carrying amount. The impairment loss would be based on the excess of the carrying value of the impaired asset over its respective fair value. To date, the Company has not recorded any impairment losses.
Leases	Leases Effective January 1, 2019, the Company adopted ASC 842 using the modified retrospective approach. Amounts presented prior to the adoption of ASC 842 have not been adjusted and continue to be reported in accordance with the Company’s historical accounting under previous lease guidance, ASC Topic 840, Leases (ASC 840). The Company determines if an arrangement includes a lease at inception. Operating leases are included in operating lease right-of-use (ROU) assets, accrued and other current liabilities and other non-current liabilities on the Company’s Condensed Consolidated Balance Sheets. Operating lease ROU assets and operating lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at commencement date. The Company uses the incremental borrowing rate based on the information available at lease commencement date in determining the present value of future payments. The operating lease ROU asset also excludes lease incentives. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise any such options. Lease expense for minimum lease payments is recognized on a straight-line basis over the lease term. The Company has elected not to apply the recognition requirements for short-term leases. For lease agreements with lease and non-lease components, the Company generally accounts for them separately.
Revenue Recognition	Revenue Recognition Effective January 1, 2018, the Company adopted ASC Topic 606, Revenue from Contracts with Customers The Company enters into corporate collaborations under which it may obtain upfront license fees, research and development funding and development and regulatory and commercial milestone payments and royalty payments. The Company’s performance obligations under these arrangements may include licenses of intellectual property, distribution rights, research and development services, delivery of manufactured product, and/or participation on joint steering committees. Licenses of intellectual property: If the license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenue from upfront license fees allocated to the license when the license is transferred to the customer and the customer is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgement to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring proportional performance for purposes of recognizing revenue from non-refundable, up-front fees. The Company evaluates the measure of proportional performance each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. 2. Summary of Significant Accounting Policies (continued) Milestone payments: At the inception of each arrangement that includes development, regulatory or commercial milestone payments, the Company evaluates whether the milestones are considered probable of being reached and estimates the amount to be included in the transaction price. There are two alternatives to use when estimating the amount of variable consideration: the expected value method and the most likely amount method. Under the expected value method, an entity considers the sum of probability-weighted amounts in a range of possible consideration amounts. Under the most likely amount method, an entity considers the single most likely amount in a range of possible consideration amounts. Whichever method is used, it should be consistently applied throughout the life of the contract; however, it is not necessary for the Company to use the same approach for all contracts. The Company expects to use the most likely amount method for development and regulatory milestone payments. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the Company’s or the licensee’s control, such as regulatory approvals, are not considered probable of being achieved until those approvals are received. The transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis. The Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, the Company re-evaluates the probability of achievement of each such milestone and any related constraint, and if necessary, adjusts its estimates of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenues and earnings in the period of adjustment. Commercial milestones and royalties: For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and in which the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue when the related sales occur. To date, the Company has not recognized any royalty revenue resulting from its collaboration arrangements. Up-front payments and fees are recorded as deferred revenue upon receipt or when due, and may require deferral of revenue recognition to a future period until the Company performs its obligations under these arrangements. Amounts payable to the Company are recorded as accounts receivable when the Company’s right to consideration is unconditional. Upon adoption of ASC 606 under the modified retrospective transition method, the Company recognized the cumulative effect of initially applying the new revenue standard of $47.3 million as an adjustment to the opening balance of accumulated deficit and an increase in deferred revenue. Revenue from government and private agency grants is recognized as the related research and development expenses are incurred and to the extent that funding is approved.
Research and Development Expenses	Research and Development Expenses All research and development expenses are recognized as incurred. Research and development expenses include, but are not limited to, salaries and related benefits, including stock-based compensation, third-party contract costs relating to research, formulation, manufacturing, preclinical study and clinical trial activities, laboratory consumables and allocated facility costs.
Clinical Trial Accruals	Clinical Trial Accruals Clinical trial costs are a component of research and development expenses. The Company accrues and expenses clinical trial activities performed by third parties based upon estimates of the percentage of work completed over the life of the individual study in accordance with agreements established with clinical research organizations and clinical trial sites. The Company determines the estimates through discussions with internal clinical personnel and external service providers as to the progress or stage of completion of trials or services and the agreed-upon fee to be paid for such services. Nonrefundable advance payments for goods and services that will be used or rendered in future research and development activities, are deferred and recognized as expense in the period that the related goods are delivered or services are performed.
Stock-Based Compensation	Stock-Based Compensation The Company measures stock-based compensation cost at the grant date based on the fair value of the award, and recognizes the expense over the award’s vesting periods on a straight-line basis. The fair value of a stock option is estimated using the Black-Scholes valuation model, which requires that, at the date of grant, assumptions are made with respect to the expected life of the option, the volatility of the fair value of the Company’s common stock, the risk-free interest rate and the expected dividend yield of the Company’s common stock. The fair value of a restricted stock unit (RSU) and restricted stock award (RSA) is valued at the closing price of the Company’s common stock on the date of the grant. Because stock compensation expense is based on awards ultimately expected to vest, it has been reduced by an estimate for future forfeitures. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. On January 1, 2019 the Company adopted Accounting Standards Update (ASU) No. 2018-07, Compensation – Stock Compensation
Comprehensive Loss	Comprehensive Loss Comprehensive loss comprises net loss and other comprehensive income (loss). For the periods presented, other comprehensive income (loss) consists of unrealized gains (losses) on the Company’s available-for-sale securities. For the year ended December 31, 2019, amounts reclassified from accumulated other comprehensive income (loss) to net loss for unrealized gains on available-for-sale securities were not significant, and were recorded as part of other income, net in the Consolidated Statements of Operations. For the years ended December 31, 2020 and 2018, there were no sales of investments, and therefore there were no reclassifications
Income Taxes	Income Taxes The Company uses the liability method for income taxes, whereby deferred tax assets and liabilities are determined based on the differences between the financial reporting and tax reporting bases of assets and liabilities and are measured using enacted tax rates and laws that are expected to be in effect when the differences are expected to reverse. Valuation allowances are provided when the expected realization for the deferred tax assets does not meet the more-likely-than-not criteria. The Company accounts for uncertain tax positions in the financial statements when it is not more likely than not that the position will be sustained upon examination by the tax authorities. Such tax positions must initially and subsequently be measured at the largest amount of tax benefit that has a greater than 50% likelihood of being realized upon ultimate settlement with the tax authority assuming full knowledge of the position and relevant facts. The Company’s policy is to recognize any interest and penalties related to unrecognized tax benefits in income tax expense.
Net Loss Per Share	Net Loss Per Share Basic net loss per common share is computed by dividing net loss attributable to common stockholders by the weighted-average number of common shares outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share is computed by dividing net loss attributable to common stockholders by the sum of the weighted-average number of common shares outstanding and dilutive common stock equivalent shares outstanding for the period. The Company’s potentially dilutive common stock equivalent shares, which include incremental common shares issuable upon (i) the exercise of outstanding stock options and warrants, (ii) vesting of RSUs and RSAs, and (iii) the purchase from contributions to the 2012 Employee Stock Purchase Plan (the ESPP) (calculated based on the treasury stock method), are only included in the calculation of diluted net loss per share when their effect is dilutive. The following potentially dilutive securities were excluded from the calculation of diluted net loss per share due to their anti-dilutive effect (in thousands): Year Ended December 31, 2020 2019 2018 Options to purchase common stock, including purchases from contributions to ESPP 7,118 9,304 10,731 Restricted stock units 406 369 440 Restricted stock awards 14 31 27 Warrants to purchase common stock (1) 150 150 150 7,688 9,854 11,348 (1) In 2012, the Company issued a warrant with a ten-year
Recent Accounting Pronouncements	Recent Accounting Pronouncements In June 2016, the Financial Accounting Standard Board ( Financial Instruments – Credit Losses: Measurement of Credit Losses on Financial Instruments The Company has reviewed other recent accounting pronouncements and concluded they are either not applicable to the business or that no material effect is expected on the consolidated financial statements as a result of future adoption.
Fair Value of Financial Assets and Liabilities	The Company determines the fair value of financial assets and liabilities using three levels of inputs as follows: Level 1—Inputs which include quoted prices in active markets for identical assets and liabilities. Level 2—Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Potentially Dilutive Securities Excluded from Calculation of Diluted Net Loss per Share Due to Anti-Dilutive Effect	The following potentially dilutive securities were excluded from the calculation of diluted net loss per share due to their anti-dilutive effect (in thousands): Year Ended December 31, 2020 2019 2018 Options to purchase common stock, including purchases from contributions to ESPP 7,118 9,304 10,731 Restricted stock units 406 369 440 Restricted stock awards 14 31 27 Warrants to purchase common stock (1) 150 150 150 7,688 9,854 11,348 (1) In 2012, the Company issued a warrant with a ten-year

Cash Equivalents, Restricted _2

Cash Equivalents, Restricted Cash and Investments (Tables)	12 Months Ended
	Dec. 31, 2020
Investments Debt And Equity Securities [Abstract]
Summary of Reconciliation of Cash, Cash Equivalents and Restricted Cash	The following table provides a reconciliation of cash, cash equivalents and restricted cash shown in the Consolidated Statements of Cash Flows (in thousands): December 31, 2020 2019 Cash and cash equivalents $ 32,297 $ 39,179 Restricted cash included in Other assets 1,080 1,080 Total cash, cash equivalents and restricted cash $ 33,377 $ 40,259
Amortized Cost and Fair Value of Cash Equivalents and Investments	The amortized cost and fair value of cash equivalents and investments at December 31, 2020 and 2019 were as follows (in thousands): December 31, 2020 Amortized Gross Unrealized Fair Cost Gains Losses Value Money market fund $ 30,139 $ — $ — $ 30,139 U.S. treasury securities 176,625 60 — 176,685 Government-sponsored agencies 12,500 — — 12,500 Commercial paper 140,364 — — 140,364 Asset-backed securities 25,706 23 — 25,729 Corporate debt securities 72,764 38 (7 ) 72,795 Total available-for-sale securities $ 458,098 $ 121 $ (7 ) $ 458,212 Classified as: Cash equivalents $ 30,139 Short-term investments 404,273 Long-term investments 23,800 Total available-for-sale securities $ 458,212 3. Cash Equivalents, Restricted Cash and Investments (continued) December 31, 2019 Amortized Gross Unrealized Fair Cost Gains Losses Value Money market fund $ 30,353 $ — $ — $ 30,353 U.S. treasury securities 40,245 47 — 40,292 Commercial paper 12,429 — — 12,429 Asset-backed securities 25,436 50 — 25,486 Corporate debt securities 84,605 225 (4 ) 84,826 Total available-for-sale securities $ 193,068 $ 322 $ (4 ) $ 193,386 Classified as: Cash equivalents $ 30,325 Short-term investments 133,607 Long-term investments 29,454 Total available-for-sale securities $ 193,386

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements of Company's Financial Assets	The Company’s financial assets subject to fair value measurements on a recurring basis and the level of inputs used in such measurements were as follows as of December 31, 2020 and 2019 (in thousands): December 31, 2020 Description Level 1 Level 2 Level 3 Total Money market fund $ 30,139 $ — $ — $ 30,139 U.S. treasury securities — 176,685 — 176,685 Government-sponsored agencies — 12,500 — 12,500 Commercial paper — 140,364 — 140,364 Asset-backed securities — 25,729 — 25,729 Corporate debt securities — 72,795 — 72,795 Total assets $ 30,139 $ 428,073 $ — $ 458,212 December 31, 2019 Description Level 1 Level 2 Level 3 Total Money market fund $ 30,353 $ — $ — $ 30,353 U.S. treasury securities — 40,292 — 40,292 Commercial paper — 12,429 — 12,429 Asset-backed securities — 25,486 — 25,486 Corporate debt securities — 84,826 — 84,826 Total assets $ 30,353 $ 163,033 $ — $ 193,386
Summary of Carrying Amount And Estimated Fair Value of Financial Instruments	The carrying amount and estimated fair value of financial instruments not recorded at fair value at December 31, 2020 and 2019 were as follows (in thousands): December 31, December 31, 2020 2019 Carrying Amount Estimated Fair Value Carrying Amount Estimated Fair Value Long-term debt, net (1) $ 24,401 $ 25,332 $ 19,786 $ 20,253 (1) Carrying amounts of long-term debt were net of unamortized debt discounts of $599 and $214 as of December 31, 2020 and 2019, respectively.

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2020
Property Plant And Equipment [Abstract]
Property and Equipment	Property and equipment consist of the following (in thousands): December 31, 2020 2019 Lab equipment $ 6,098 $ 6,747 Computer equipment and software 738 1,865 Furniture and fixtures 381 552 Tenant improvements 24,826 1,607 32,043 10,771 Less: accumulated depreciation (6,883 ) (8,617 ) $ 25,160 $ 2,154

Accrued and Other Current Lia_2

Accrued and Other Current Liabilities (Tables)	12 Months Ended
	Dec. 31, 2020
Payables And Accruals [Abstract]
Schedule of Accrued and Other Current Liabilities	Accrued and other current liabilities consist of the following (in thousands): December 31, 2020 2019 Research and development related $ 11,062 $ 13,100 Compensation related 5,498 3,608 Consulting and professional services 1,690 1,094 Current portion of operating lease liability 845 1,503 Other 699 501 $ 19,794 $ 19,806

Long-term Debt (Tables)

Long-term Debt (Tables)	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Schedule of Future Minimum Principal Payments Related to Credit Facility	Future minimum principal payments, which exclude the end of term charge, as of December 31, 2020 are as follows (in thousands): Amounts Year ending December 31: 2021 $ 6,389 2022 14,666 2023 3,353 2024 592 Total minimum payments 25,000 Less: amount representing debt discount (599 ) Present value of remaining debt payments 24,401 Less: current portion (6,302 ) Non-current portion $ 18,099

Commitments (Tables)

Commitments (Tables)	12 Months Ended
	Dec. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Schedule of Balance Sheet Classification of the Company's Operating Lease Assets and Liabilities	The balance sheet classification of the Company’s operating lease assets and liabilities was as follows (in thousands): December 31, 2020 2019 Balance Sheet Assets: Operating lease right-of-use assets $ 26,911 $ 1,704 Liabilities: Operating lease liabilities: Accrued and other current liabilities (1) $ 845 $ 1,503 Non-current lease liabilities 38,671 566 (1) Includes current portion of operating lease liabilities.
Schedule of Operating Expenses in the Company's Condensed Consolidated Statements of Operations	The component of lease costs, which was included in operating expenses in the Company’s Consolidated Statements of Operations, was as follows (in thousands): Year Ended December 31, 2020 2019 2018 Operating lease cost $ 4,648 $ 1,295 $ 1,072
Schedule of Future Minimum Lease Payments Under all Noncancelable Operating Leases	Future minimum lease payments under all noncancelable operating leases as of December 31, 2020, are as follows (in thousands): Operating leases Year ending December 31: 2021 $ 5,210 2022 7,316 2023 7,516 2024 7,721 2025 7,932 Thereafter 44,585 Total minimum payments 80,280 Less: interest (30,296 ) Less: future tenant improvement reimbursements (10,468 ) Present value of lease liabilities $ 39,516

Related-Party Transactions (Tab

Related-Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2020
Related Party Transactions [Abstract]
Schedule of Contract Assets and Liabilities and Changes in Contract Balances	9. Related Party Transactions (continued) The following table presents the contract assets and liabilities for all of the Company’s revenue contracts as of the following dates (in thousands): December 31, 2020 2019 Contract asset: Accounts receivable $ 32 $ — Contract liability: Deferred revenue (36,587 ) (100,837 ) During the years ended December 31, 2020, 2019 and 2018, the Company recognized the following revenue as a result of changes in the contract asset and the contract liability balances (in thousands): Year Ended December 31, 2020 2019 2018 Revenue recognized in the period from: Amount included in contract liability at the beginning of the period $ 64,250 $ 35,781 $ 39,815 Performance obligations satisfied (or partially satisfied) in previous periods $ (40,647 ) $ (2,251 ) $ (3,357 )

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Restricted Stock Activity	The activity for restricted stock is summarized as follows: Shares Weighted- Average Grant-Date Fair Value Balance at December 31, 2019 399,823 $ 10.54 Granted 280,360 49.26 Vested (248,486 ) 13.32 Canceled (11,667 ) 10.95 Unvested at December 31, 2020 420,030 $ 34.73
Summary of Stock Option Activity under its Stock Plans	11. Stockholders’ Equity (continued) The following table summarizes stock option activity and related information under the Company’s Stock Plans: Available for Grant Share s Weighted Average Exercise Price Weighted Average Remaining Contractual Term (in years) Aggregate Intrinsic Value Balance at December 31, 2019 2,192,545 9,287,901 $ 9.44 Shares authorized 2,000,000 — Granted (1) (1,267,668 ) 987,308 49.52 Exercised (2) 92,459 (3,019,410 ) 9.70 Forfeited and expired (3) 153,241 (141,574 ) 23.97 Outstanding at December 31, 2020 3,170,577 7,114,225 $ 14.61 6.53 $ 336,617,882 Vested and expected to vest, net of estimated forfeiture at December 31, 2020 6,886,096 $ 14.16 6.46 $ 328,929,110 Exercisable at December 31, 2020 4,491,790 $ 8.52 5.42 $ 239,880,734 (1) The difference between shares granted in the number of shares available for grant and outstanding options represents the RSUs and RSAs granted for the period. (2) Shares presented as available for grant represents shares repurchased for tax withholding upon vesting of RSUs. (3) The difference between shares forfeited and expired in the number of shares available for grant and outstanding options represents the RSUs canceled during the period.
Stock Options Outstanding	As of December 31, 2020, stock options outstanding were as follows: Options Outstanding Exercise Price Range Shares Weighted- Average Contractual Life $3.29 - $5.95 711,839 5.38 $6.08 - $6.62 963,248 5.48 $6.66 - $8.19 1,267,114 4.45 $8.29 - $10.82 331,926 7.45 $10.86 733,395 7.17 $10.91 - $10.93 27,492 7.64 $11.02 955,222 8.12 $11.56 - $13.89 764,764 7.75 $13.94 - $46.52 847,357 6.19 $46.59 - $62.39 511,868 9.43 7,114,225 6.53
Employee Stock-based Compensation Expense Recognized	Total employee stock-based compensation expense recognized associated with restricted stock, stock options, and the ESPP, was as follows (in thousands): Year Ended December 31, 2020 2019 2018 Research and development $ 7,815 $ 4,530 $ 3,632 General and administrative 13,133 6,819 6,339 Total $ 20,948 $ 11,349 $ 9,971
Assumptions for Fair Values of Employee Stock Options Granted under Company's Stock Plans	11. Stockholders’ Equity (continued) The fair values of the employee stock options granted under the Company’s Stock Plans and the option component of the shares purchased under the ESPP during 2020, 2019 and 2018 were estimated at the date of grant using the Black-Scholes option-pricing model with the following assumptions: Employee Stock Options Employee Stock Purchase Plan 2020 2019 2018 2020 2019 2018 Dividend yield 0 % 0 % 0 % 0 % 0 % 0 % Volatility 87.4 % 71.3 % 67.8 % 118.4 % 56.4 % 73.8 % Weighted-average expected life (in years) 6.0 6.0 6.0 0.5 0.5 0.5 Risk-free interest rate 0.66 % 2.28 % 2.66 % 0.13 % 1.87 % 2.33 % Weighted-average grant date fair value $ 35.71 $ 7.54 $ 6.22 $ 25.93 $ 4.10 $ 3.73
Stock-based Compensation Expense in Connection with Grants of Stock Options to Nonemployees	Total stock-based compensation expense recognized associated with restricted stock and stock options granted to nonemployees was as follows (in thousands): Year Ended December 31, 2020 2019 2018 Research and development $ 1,892 $ 186 $ 862 General and administrative 72 103 — Total $ 1,964 $ 289 $ 862
Assumptions for Fair Values of Stock Options Granted are Calculated Related to Stock Options Granted to Nonemployees	The estimated fair values of the stock options granted are calculated at each reporting date using the Black-Scholes option-pricing model, with the following assumptions: Year Ended December 31, 2020 2019 2018 Dividend yield 0% 0% 0% Volatility 87% 68-87% 67-68% Weighted-average expected life (in years) 6.0 5.5-6.0 5.7-9.9 Risk-free interest rate 0.84% 1.6-2.2% 2.7-3.0%

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Components of Income Tax (Benefit) Expense	The Company’s loss before tax is only attributable to U.S. operations. The components of the income tax (benefit) expense are as follows (in thousands): Year Ended December 31, 2020 2019 2018 Current (benefit from) provision for income taxes: Federal $ — $ — $ — State — — — Total current (benefit from) provision for income taxes — — — Deferred (benefit from) provision for income taxes: — — — Federal — — — State — — — Total deferred tax (benefit from) provision for income taxes — — — (Benefit from) provision for income taxes $ — $ — $ —
Reconciliation of the Federal Statutory Income Tax Rate to the Company's Effective Income Tax Rate	A reconciliation of the federal statutory income tax rate to the Company’s effective income tax rate is as follows: Year Ended December 31, 2020 2019 2018 Federal statutory income tax rate (21.0 %) (21.0 %) (21.0 %) Permanent items 2.1 1.3 1.6 Excess tax benefit for stock-based compensation (40.9 ) (13.3 ) (2.8 ) Tax credits (13.4 ) (38.3 ) (3.5 ) Change in valuation allowance 70.4 70.3 24.5 Non-deductible executive compensation 2.7 1.0 0.6 Other 0.1 — 0.6 (Benefit from) provision for income taxes — % — % — %
Tax Effects of Temporary Differences and Carryforwards that Give Rise to Significant Portions of the Deferred Tax Assets	13. Income Taxes (continued) The tax effects of temporary differences and carryforwards that give rise to significant portions of the deferred tax assets consist of the following (in thousands): December 31, 2020 2019 Deferred tax assets: Net operating loss carryforwards $ 120,347 $ 76,033 Tax credits 49,229 39,625 Amortization of deferred stock compensation - non- qualified 4,165 5,172 Reserves and accruals 1,770 1,528 Deferred revenue 7,684 20,312 Depreciation and amortization — 15 Lease liability 8,299 434 Gross deferred tax assets 191,494 143,119 Less: valuation allowance (183,948 ) (142,761 ) Total deferred tax assets 7,546 358 Deferred tax liabilities: Property, Plant and Equipment (1,894 ) — Right of use asset (5,652 ) (358 ) Total deferred tax liabilities (7,546 ) (358 ) Net deferred tax assets $ — $ —
Reconciliation of the Company's Unrecognized Tax Benefits	13. Income Taxes (continued) A reconciliation of the Company’s unrecognized tax benefits for the years ended December 31, 2020, 2019 and 2018, is as follows (in thousands): Unrecognized Income Tax Benefits Balance as of December 31, 2018 $ 9,714 Additions for current tax positions 3,455 Additions for prior tax positions 16,007 Balance as of December 31, 2019 29,176 Additions for current tax positions 1,317 Releases (29 ) Balance as of December 31, 2020 $ 30,464

Selected Quarterly Financial _2

Selected Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Results from Operations	Selected quarterly results from operations for the years ended December 31, 2020 and 2019 are as follows (in thousands except per share amounts): 2020 Quarter Ended March 31 June 30 September 30 December 31 Revenue $ 6,008 $ 49,440 $ 5,085 $ 4,358 Net income (loss) $ (21,687 ) $ 20,267 $ (24,060 ) $ (29,876 ) Basic net income (loss) per share $ (0.35 ) $ 0.32 $ (0.35 ) $ (0.43 ) Diluted net income (loss) per share $ (0.35 ) $ 0.29 $ (0.35 ) $ (0.43 ) 2019 Quarter Ended March 31 June 30 September 30 December 31 Revenue $ 8,327 $ 7,173 $ 10,581 $ 10,047 Net loss $ (11,949 ) $ (15,150 ) $ (12,862 ) $ (15,528 ) Basic and diluted net loss per share $ (0.23 ) $ (0.26 ) $ (0.22 ) $ (0.26 )

Description of Business - Addit

Description of Business - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2020Segment
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Number of Operating Segment	1

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Significant Accounting Policies [Line Items]
Percentage of contract revenue as total revenue	99.20%	99.50%	100.00%
Impairment loss on long lived assets	$ 0
Reclassification adjustment from accumulated other comprehensive loss for unrealized gain (loss) realized upon the sale of available-for-sale securities	0	$ 0	$ 0
Accounting Standards Update 2014-09 [Member]
Significant Accounting Policies [Line Items]
Cumulative effect to opening balance of accumulated deficit on adoption of accounting standard	47,300,000
Increase in deferred revenue	$ 47,300,000
Minimum [Member]
Significant Accounting Policies [Line Items]
Estimated useful lives of assets	5 years
Maximum [Member]
Significant Accounting Policies [Line Items]
Estimated useful lives of assets	7 years

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Potentially Dilutive Securities Excluded from Calculation of Diluted Net Loss per Share Due to Anti-Dilutive Effect (Detail) - shares	12 Months Ended
	Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2012
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	7,688,000		9,854,000		11,348,000
Options to Purchase Common Stock, Including Purchases from Contributions to ESPP [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	7,118,000		9,304,000		10,731,000
Unvested Restricted Stock Units (RSUs) [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	406,000		369,000		440,000
Restricted Stock Awards [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	14,000		31,000		27,000
Warrants to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	150,000	[1]	150,000	[1]	150,000	[1]	150,000
[1]	In 2012, the Company issued a warrant with a ten-year

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Potentially Dilutive Securities Excluded from Calculation of Diluted Net Loss per Share Due to Anti-Dilutive Effect (Parenthetical) (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2012
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Issued warrant to purchase common stock, amount	7,688,000		9,854,000		11,348,000
Warrants to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Issued warrant to purchase common stock, amount	150,000	[1]	150,000	[1]	150,000	[1]	150,000
Warrant term							10 years
Issued warrant to purchase common stock, exercise price							$ 20
[1]	In 2012, the Company issued a warrant with a ten-year

Cash Equivalents, Restricted _3

Cash Equivalents, Restricted Cash and Investments - Summary of Reconciliation of Cash, Cash Equivalents and Restricted Cash (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash and cash equivalents	$ 32,297	$ 39,179
Total cash, cash equivalents and restricted cash	33,377	40,259	$ 28,088	$ 40,020
Other Assets [Member]
Restricted cash included in Other assets	$ 1,080	$ 1,080

Cash Equivalents, Restricted _4

Cash Equivalents, Restricted Cash and Investments - Amortized Cost and Fair Value of Cash Equivalents and Investments (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 458,098	$ 193,068
Gross Unrealized Gains	121	322
Gross Unrealized Losses	(7)	(4)
Available-for-sale Securities	458,212	193,386
Money Market Fund [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	30,139	30,353
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Available-for-sale Securities	30,139	30,353
U.S. Treasury Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	176,625	40,245
Gross Unrealized Gains	60	47
Gross Unrealized Losses	0	0
Available-for-sale Securities	176,685	40,292
Government-Sponsored Agencies [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	12,500
Gross Unrealized Gains	0
Gross Unrealized Losses	0
Available-for-sale Securities	12,500
Commercial Paper [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	140,364	12,429
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Available-for-sale Securities	140,364	12,429
Asset-backed Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	25,706	25,436
Gross Unrealized Gains	23	50
Gross Unrealized Losses	0	0
Available-for-sale Securities	25,729	25,486
Corporate Debt Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	72,764	84,605
Gross Unrealized Gains	38	225
Gross Unrealized Losses	(7)	(4)
Available-for-sale Securities	$ 72,795	$ 84,826

Cash Equivalents, Restricted _5

Cash Equivalents, Restricted Cash and Investments - Amortized Cost and Fair Value of Cash Equivalents and Investments 2 (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Cash and Cash Equivalents [Abstract]
Cash equivalents	$ 30,139	$ 30,325
Short-term investments	404,273	133,607
Long-term investments	23,800	29,454
Total available-for-sale securities	$ 458,212	$ 193,386

Cash Equivalents, Restricted _6

Cash Equivalents, Restricted Cash and Investments - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2020USD ($)Investment	Dec. 31, 2019USD ($)
Cash And Cash Equivalents [Abstract]
Maturity period available-for-sale securities	less than two years
Significant realized gains or losses on available-for-sale securities	$ 0
Cash	$ 2,200,000	$ 8,900,000
Number of available-for-sale securities in a continuous unrealized loss position for more than 12 months | Investment	0

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value Measurements of Company's Financial Assets (Detail) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	$ 458,212	$ 193,386
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	30,139	30,353
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	428,073	163,033
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Money Market Fund [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	30,139	30,353
Money Market Fund [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	30,139	30,353
Money Market Fund [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Money Market Fund [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
U.S. Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	176,685	40,292
U.S. Treasury Securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
U.S. Treasury Securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	176,685	40,292
U.S. Treasury Securities [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Government-Sponsored Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	12,500
Government-Sponsored Agencies [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0
Government-Sponsored Agencies [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	12,500
Government-Sponsored Agencies [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0
Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	140,364	12,429
Commercial Paper [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Commercial Paper [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	140,364	12,429
Commercial Paper [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Asset-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	25,729	25,486
Asset-backed Securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Asset-backed Securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	25,729	25,486
Asset-backed Securities [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	72,795	84,826
Corporate Debt Securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	0	0
Corporate Debt Securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	72,795	84,826
Corporate Debt Securities [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	$ 0	$ 0

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail)	Dec. 31, 2020USD ($)
Fair Value Disclosures [Abstract]
Transfers from Level 1 to Level 2 financial assets	$ 0
Transfers from Level 2 to Level 1 financial assets	$ 0

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Carrying Amount and Estimated Fair Value of Financial Instruments (Detail) - USD ($) $ in Thousands		Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Amount		$ 24,401
Term Loan [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Amount	[1]	24,401	$ 19,786
Estimated Fair Value	[1]	$ 25,332	$ 20,253
[1]	Carrying amounts of long-term debt were net of unamortized debt discounts of $599 and $214 as of December 31, 2020 and 2019, respectively.

Fair Value Measurements - Sum_2

Fair Value Measurements - Summary of Carrying Amount and Estimated Fair Value of Financial Instruments (Parenthetical) (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unamortized debt discounts	$ 599
Term Loan [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unamortized debt discounts	$ 599	$ 214

Property and Equipment - Proper

Property and Equipment - Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property and equipment	$ 32,043	$ 10,771
Less: accumulated depreciation	(6,883)	(8,617)
Net Property and equipment	25,160	2,154
Lab Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	6,098	6,747
Computer Equipment and Software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	738	1,865
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	381	552
Tenant Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	$ 24,826	$ 1,607

Accrued and Other Current Lia_3

Accrued and Other Current Liabilities (Detail) - USD ($) $ in Thousands		Dec. 31, 2020	Dec. 31, 2019
Research and development related		$ 11,062	$ 13,100
Compensation related		5,498	3,608
Consulting and professional services		1,690	1,094
Other		699	501
Accrued liabilities		19,794	19,806
Accrued and Other Current Liabilities [Member]
Current portion of operating lease liability	[1]	$ 845	$ 1,503
[1]	Includes current portion of operating lease liabilities.

Long-term Debt - Additional Inf

Long-term Debt - Additional Information (Detail)		Mar. 31, 2020	Jan. 08, 2020USD ($)Tranche	Dec. 28, 2017USD ($)	Dec. 31, 2020USD ($)	Dec. 01, 2022USD ($)	Dec. 31, 2019USD ($)
Debt Instrument [Line Items]
Line of credit facility, advance amount					$ 20,000,000
Line of credit facility, interest rate			8.50%	8.05%
Borrowings outstanding					24,401,000
Discount on borrowings					$ 599,000
Hercules Capital Inc [Member]
Debt Instrument [Line Items]
Loan commitment fee, percentage			1.00%
Purchase of common stock			$ 1,000,000
Term Loan [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity				$ 50,000,000
Line of credit facility, interest rate					8.05%
Line of credit facility, maturity date					Dec. 1, 2022
Line of credit facility, interest rate description					As of December 31, 2020, the Company had borrowed $20.0 million under the Credit Facility, with an interest rate of 8.05% per annum, and the remaining available amount had expired.
Borrowings outstanding	[1]				$ 24,401,000		$ 19,786,000
Discount on borrowings					$ 599,000		$ 214,000
Term Loan [Member] | Minimum [Member]
Debt Instrument [Line Items]
Loan commitment charge			162,500
Term Loan [Member] | Forecast [Member]
Debt Instrument [Line Items]
Payment of end term charge						$ 1,300,000
Term Loan [Member] | Wall Street Journal Prime [Member]
Debt Instrument [Line Items]
Line of credit facility, interest rate					4.75%
Term Loan Restated [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			$ 100,000,000
Line of credit facility, interest rate description					In addition, the Company may prepay advances under the Restated Credit Facility, in whole or in part, at any time, subject to a prepayment charge that ranges from 1.0% to 2.0%, depending on the timing of the prepayment. The Restated Credit Facility is secured by substantially all of the Company’s assets, excluding intellectual property.
Number of tranches | Tranche			3
Term Loan Restated [Member] | Minimum [Member]
Debt Instrument [Line Items]
Loan commitment charge			$ 520,000
Aggregate proceeds to be received from equity offering			30,000,000
Term Loan Restated [Member] | Hercules Capital Inc [Member] | Maximum [Member]
Debt Instrument [Line Items]
Amount of participation in equity financing			3,000,000
Term Loan Restated [Member] | Tranche One [Member]
Debt Instrument [Line Items]
Line of credit facility, advance amount					$ 5,000,000
Line of credit facility, interest rate		8.50%
Line of credit facility, maturity date					Feb. 1, 2024
Line of credit facility, interest rate description					Under the Restated Credit Facility, the Company borrowed $5.0 million from the first tranche with an interest rate of 8.50% per annum as of December 31, 2020.  Advances under the Restated Credit Facility bear an initial interest rate equal to the greater of either (i) 8.50% plus the Prime Rate minus 5.25%, and (ii) 8.50%, which may be reduced upon the Company achieving certain cumulative net avacopan revenue levels. For advances under the Restated Credit Facility, the Company will make interest only payments through September 1, 2022 and will then repay the principal balance and interest on the advances in equal monthly installments through February 1, 2024. Upon satisfaction of certain conditions, the interest-only payment period and the principal balance repayment period may be extended.  In addition, the Company will pay an end of term charge of 7.15% of the aggregate amount of the advances under the Restated Credit Facility
End of term charge advances, percentage					7.15%
Term Loan Restated [Member] | Wall Street Journal Prime [Member] | Tranche One [Member]
Debt Instrument [Line Items]
Line of credit facility, interest rate					5.25%
Through December 15, 2020 [Member] | Tranche One [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			40,000,000
Through December 15, 2020 [Member] | Tranche One [Member] | Avacopan New Drug Application
Debt Instrument [Line Items]
Line of credit facility, capacity available for specific purpose other than for trade purchases			20,000,000
Through December 15, 2021 [Member] | Tranche Two [Member] | Avacopan New Drug Application
Debt Instrument [Line Items]
Restated credit facility, maximum borrowing capacity			30,000,000
Through December 15, 2022 [Member] | Tranche Three [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			$ 30,000,000
[1]	Carrying amounts of long-term debt were net of unamortized debt discounts of $599 and $214 as of December 31, 2020 and 2019, respectively.

Long-term Debt - Schedule of Fu

Long-term Debt - Schedule of Future Minimum Principal Payments Related to the Credit Facility (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
2021	$ 6,389
2022	14,666
2023	3,353
2024	592
Total minimum payments	25,000
Less: amount representing debt discount	(599)
Long-term debt, net	24,401
Less: current portion	(6,302)	$ 0
Long-term debt, Non-current portion	$ 18,099	$ 19,786

Commitments - Additional Inform

Commitments - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)ft²	Dec. 31, 2019USD ($)
Operating Leased Assets [Line Items]
Initial annual base rent expense	$ 6.5
Incremental percentage of annual lease rent	3.00%
Operating lease contract	10 years
Expiration date	2031-02
Tenant improvement allowance	$ 15.4
Proceeds from Additional Tenant Allowance	$ 4.8
Operating lease, option to extend	an option to extend the lease for five years
Additional tenant improvement allowance	7.00%
Tenant improvement allowance received	$ 9.3
Operating lease new facility commence	June 2020
Operating Lease, Payments	$ 1.7	$ 1.3
Operating Lease, Weighted Average Remaining Lease Term	10 years
Operating Lease, Weighted Average Discount Rate, Percent	9.50%
Third Amendment May 2019 [Member]
Operating Leased Assets [Line Items]
Expiration date	2021-04
Letter of Credit [Member]
Operating Leased Assets [Line Items]
Security deposit	$ 1.1
San Carlos California [Member]
Operating Leased Assets [Line Items]
Area of Land | ft²	96,463
Discounted lease	Following a six month period of discounted rent

Commitments - Schedule of Balan

Commitments - Schedule of Balance Sheet Classification of the Company's Operating Lease Assets and Liabilities (Details) - USD ($) $ in Thousands		Dec. 31, 2020	Dec. 31, 2019
Operating lease right-of-use assets		$ 26,911	$ 1,704
Operating lease liabilities:
Non-current lease liabilities		38,671	566
Accrued And Other Liabilities Current [Member]
Operating lease liabilities:
Accrued and other current liabilities	[1]	$ 845	$ 1,503
[1]	Includes current portion of operating lease liabilities.

Commitments - Schedule of Opera

Commitments - Schedule of Operating Expenses in the Company's Condensed Consolidated Statements of Operations (Details 1) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Operating lease cost	$ 4,648	$ 1,295	$ 1,072

Commitments - Schedule of Futur

Commitments - Schedule of Future Minimum Lease Payments Under all Noncancelable Operating Leases (Details 2) $ in Thousands	Dec. 31, 2020USD ($)
Commitments And Contingencies Disclosure [Abstract]
2021	$ 5,210
2022	7,316
2023	7,516
2024	7,721
2025	7,932
Thereafter	44,585
Total minimum payments	80,280
Less: interest	(30,296)
Less: future tenant improvement reimbursements	(10,468)
Present value of lease liabilities	$ 39,516
Operating Lease, Liability, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesMember

Related-Party Transactions - Ad

Related-Party Transactions - Additional Information (Detail) - USD ($)	Dec. 28, 2017	Oct. 31, 2020	Jun. 30, 2018	Dec. 31, 2017	Feb. 28, 2017	May 31, 2016	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	May 09, 2016
Related Party Transaction [Line Items]
Non refundable upfront payments received						$ 85,000,000
Non refundable upfront payment received in equity investment, shares						3,333,333
Performance obligations satisfied (or partially satisfied) in previous periods				$ 50,000,000				$ (40,647,000)	$ (2,251,000)	$ (3,357,000)
Transaction price								153,000,000				$ 78,000,000
Upfront payments received						$ 78,000,000
Non refundable upfront payments allocated for issuance of common stock						$ 7,000,000
Issuance of common stock, per share value						$ 2.10
Upfront cash commitment					$ 20,000,000
Other current liabilities to related party		$ 6,200
Revenues recognized								0
Collaboration and license revenue from related party								64,392,000	35,952,000	42,875,000
Collaboration and license revenue from related party								64,392,000	35,952,000	42,875,000
Avacopan Agreement [Member]
Related Party Transaction [Line Items]
Non refundable upfront payments received					$ 20,000,000	$ 85,000,000
Non refundable upfront payment received in cash						60,000,000
Non refundable upfront payment received in equity investment						$ 25,000,000
Share price of common stock in equity investment						$ 7.50
Non refundable upfront payment received in equity investment, shares						3,333,333
Performance obligations satisfied (or partially satisfied) in previous periods				$ 50,000,000
Collaboration and license revenue from related party								13,000,000	29,500,000	37,100,000
Collaboration and license revenue from related party								13,000,000	29,500,000	37,100,000
Avacopan Agreement [Member] | Maximum [Member]
Related Party Transaction [Line Items]
Potential milestone payments receivable									460,000,000
Avacopan Letter Agreement [Member]
Related Party Transaction [Line Items]
Non refundable payment for expanded rights	$ 5,000,000		$ 5,000,000
CCX140 Agreement [Member]
Related Party Transaction [Line Items]
Non refundable payment for expanded rights			5,000,000					5,000,000			$ 50,000,000
Performance obligations satisfied (or partially satisfied) in previous periods								800,000
Transaction price								66,500,000
Upfront payments received								50,000,000
Non refundable upfront commitment			$ 11,500,000
Other current liabilities to related party							$ 6,200,000
Collaboration and license revenue from related party								51,400,000	6,400,000	5,800,000
Deferred Revenue, Recognized							46,700,000
Development Funding, Reduction							$ 47,200,000
Collaboration and license revenue from related party								$ 51,400,000	$ 6,400,000	$ 5,800,000
Vifor [Member]
Related Party Transaction [Line Items]
Purchase of Common stock, shares								9,194,085
Vifor [Member] | CCX140 Agreement [Member]
Related Party Transaction [Line Items]
Development funding								$ 11,500,000

Related-Party Transactions - Sc

Related-Party Transactions - Schedule of Contract Assets and Liabilities and Changes in Contract Balances (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accounts Receivable Net [Member]
Contract asset:
Contract asset	$ 32	$ 0
Deferred Revenue [Member]
Contract liability:
Contract liability	$ (36,587)	$ (100,837)

Related-Party Transactions - _2

Related-Party Transactions - Schedule of Contract Assets and Liabilities Changes (Detail) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Related Party Transactions [Abstract]
Amount included in contract liability at the beginning of the period		$ 64,250	$ 35,781	$ 39,815
Performance obligations satisfied (or partially satisfied) in previous periods	$ 50,000	$ (40,647)	$ (2,251)	$ (3,357)

Government Grant - Additional I

Government Grant - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2020	Dec. 31, 2019
Government Grant [Member]
Grant revenue		$ 0.5	$ 0.2
Accounts Receivable, Related Parties		$ 0.1	$ 0.2
U.S. Food and Drug Administration [Member]
Grant Received	$ 1
Grant Term	2 years

Stockholders' Equity - Stock Op

Stockholders' Equity - Stock Options - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	12 Months Ended
	Nov. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Feb. 29, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company's incremental common stock shares reserved for issuance		2,000,000
Total intrinsic value of options exercised		$ 123.3	$ 48.4	$ 9.8
Restricted Stocks [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted Average Grant-Date Fair Value, Granted		$ 49.26		$ 11.54	$ 11.32
Total fair value of restricted stock vested		$ 11.4	$ 3.1	$ 2.4
Unrecognized compensation expenses		$ 6.4
Unrecognized compensation expense, weighted-average period		1 year 6 months
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expenses		$ 33.8
Unrecognized compensation expense, weighted-average period		2 years 3 months 18 days
2012 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance		17,440,000
Shares available for issuance under plan annual increase rate		4.00%
Company's incremental common stock shares reserved for issuance	2,000,000
2012 Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for issuance under Plan annual increase						2,000,000
Stock Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum vesting term		10 years
Outstanding options vest		4 years
Stock Plans [Member] | First Anniversary [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total grant vesting		25.00%
Stock Plans [Member] | Monthly After First Anniversary [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total grant vesting		2.77778%
Stock Plans [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise prices date of grant fair value rate		100.00%
Nonstatutory options granted exercise price		85.00%

Stockholders' Equity - Restrict

Stockholders' Equity - Restricted Stock Activity (Detail) - Restricted Stocks [Member] - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Unvested, Beginning Balance	399,823
Shares, Granted	280,360
Shares, Vested	(248,486)
Shares, Canceled	(11,667)
Shares, Unvested, Ending Balance	420,030
Weighted Average Grant-Date Fair Value, Unvested, Beginning Balance	$ 10.54
Weighted Average Grant-Date Fair Value, Granted	49.26	$ 11.54	$ 11.32
Weighted Average Grant-Date Fair Value, Vested	13.32
Weighted Average Grant-Date Fair Value, Canceled	10.95
Weighted Average Grant-Date Fair Value, Unvested, Ending Balance	$ 34.73

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Stock Option Activity under its Stock Plans (Detail)	12 Months Ended
	Dec. 31, 2020USD ($)$ / sharesshares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares Available for Grant, Outstanding Beginning Balance	2,192,545
Available for Grant, Shares authorized	2,000,000
Shares Available for Grant, Granted	(1,267,668)
Shares Available for Grant, Exercised	92,459
Shares Available for Grant, Forfeited and expired	153,241
Shares Available for Grant, Outstanding Ending Balance	3,170,577
Shares, Options Outstanding, Beginning Balance	9,287,901
Shares, Options Outstanding, authorized	0
Shares, Options Outstanding, Granted	987,308
Shares, Options Outstanding, Exercised	(3,019,410)
Shares, Options Outstanding, Forfeited and expired	(141,574)
Shares, Options Outstanding, Ending Balance	7,114,225
Shares, Vested and expected to vest, net of estimated forfeiture at December 31, 2020	6,886,096
Shares, Exercisable at December 31, 2020	4,491,790
Weighted Average Exercise Price, Options Outstanding, Beginning Balance | $ / shares	$ 9.44
Weighted Average Exercise Price, Options Outstanding, Granted | $ / shares	49.52
Weighted Average Exercise Price, Options Outstanding, Exercised | $ / shares	9.70
Weighted Average Exercise Price, Options Outstanding, Forfeited and expired | $ / shares	23.97
Weighted Average Exercise Price, Options Outstanding, Ending Balance | $ / shares	14.61
Weighted Average Exercise Price, Vested and expected to vest, net of estimated forfeiture at December 31, 2020 | $ / shares	14.16
Weighted Average Exercise Price, Exercisable at December 31, 2020 | $ / shares	$ 8.52
Options Outstanding, Weighted Average Remaining Contractual Term	6 years 6 months 10 days
Weighted Average Remaining Contractual Term, Vested and expected to vest, net of estimated forfeiture at December 31, 2020	6 years 5 months 15 days
Weighted Average Remaining Contractual Term, Exercisable at December 31, 2020	5 years 5 months 1 day
Aggregate Intrinsic Value, Outstanding, Ending Balance | $	$ 336,617,882
Aggregate Intrinsic Value, Vested and expected to vest, net of estimated forfeiture at December 31, 2020 | $	328,929,110
Aggregate Intrinsic Value, Exercisable at December 31, 2020 | $	$ 239,880,734

Stockholders' Equity - Stock _2

Stockholders' Equity - Stock Options Outstanding (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Options Outstanding , Shares	7,114,225	9,287,901
Weighted Average Contractual Term, Outstanding	6 years 6 months 10 days
Range 1 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price Range, Lower	$ 3.29
Exercise Price Range, Upper	$ 5.95
Options Outstanding , Shares	711,839
Weighted Average Contractual Term, Outstanding	5 years 4 months 17 days
Range 2 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price Range, Lower	$ 6.08
Exercise Price Range, Upper	$ 6.62
Options Outstanding , Shares	963,248
Weighted Average Contractual Term, Outstanding	5 years 5 months 23 days
Range 3 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price Range, Lower	$ 6.66
Exercise Price Range, Upper	$ 8.19
Options Outstanding , Shares	1,267,114
Weighted Average Contractual Term, Outstanding	4 years 5 months 12 days
Range 4 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price Range, Lower	$ 8.29
Exercise Price Range, Upper	$ 10.82
Options Outstanding , Shares	331,926
Weighted Average Contractual Term, Outstanding	7 years 5 months 12 days
Range 5 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price Range, Lower	$ 10.86
Exercise Price Range, Upper	$ 10.86
Options Outstanding , Shares	733,395
Weighted Average Contractual Term, Outstanding	7 years 2 months 1 day
Range 6 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price Range, Lower	$ 10.91
Exercise Price Range, Upper	$ 10.93
Options Outstanding , Shares	27,492
Weighted Average Contractual Term, Outstanding	7 years 7 months 20 days
Range 7 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price Range, Lower	$ 11.02
Exercise Price Range, Upper	$ 11.02
Options Outstanding , Shares	955,222
Weighted Average Contractual Term, Outstanding	8 years 1 month 13 days
Range 8 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price Range, Lower	$ 11.56
Exercise Price Range, Upper	$ 13.89
Options Outstanding , Shares	764,764
Weighted Average Contractual Term, Outstanding	7 years 9 months
Range 9 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price Range, Lower	$ 13.94
Exercise Price Range, Upper	$ 46.52
Options Outstanding , Shares	847,357
Weighted Average Contractual Term, Outstanding	6 years 2 months 8 days
Range 10 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise Price Range, Lower	$ 46.59
Exercise Price Range, Upper	$ 62.39
Options Outstanding , Shares	511,868
Weighted Average Contractual Term, Outstanding	9 years 5 months 4 days

Stockholders' Equity - Employee

Stockholders' Equity - Employee Stock Purchase Plan - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended	12 Months Ended
	Nov. 30, 2020	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Feb. 29, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for issuance under Plan			3,170,577	2,192,545
Aggregate limit of common stock			200,000,000	200,000,000
Company's incremental common stock shares reserved for issuance			2,000,000
Stock options grant shares approved for issuance-Non Employee			21,400	82,011	28,534
Common stock, par value			$ 0.001	$ 0.001	$ 0.001
Stock issued during period, shares, new issues				6,491,196
Proceeds from issuance of common stock			$ 325,654	$ 73,276	$ 0
Issuance of common stock throughEquity Distribution Agreement,net of issuance costs (Note 11), shares				6,491,196
Follow On Equity Public Offering [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock issued during period, shares, new issues		5,980,000
Proceeds from issuance of common stock		$ 325,700
Issuance of common stock throughEquity Distribution Agreement,net of issuance costs (Note 11), shares		5,980,000
Common stock issued per share		$ 58
Equity Distribution Agreement [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity distribution agreement offering price					$ 75,000
Restricted Stocks [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expenses			$ 6,400
Unrecognized compensation expense, weighted-average period			1 year 6 months
Stock options grant shares approved for issuance-Non Employee			66,000
Restricted Stocks [Member] | Performance Conditions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options grant shares approved for issuance-Non Employee			35,000
ESPP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for issuance under Plan			843,737
Common stock initially reserved for issuance						300,000
Shares available for issuance under plan annual increase rate						1.00%
Company's incremental common stock shares reserved for issuance	300,000
Common stock issued to employees			79,161	71,653	88,784
Unrecognized compensation expenses			$ 200
Unrecognized compensation expense, weighted-average period			4 months 24 days
ESPP [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for issuance under Plan			1,700,000
Aggregate limit of common stock						3,000,000

Stockholders' Equity - Employ_2

Stockholders' Equity - Employee Stock- based Compensation Expense Recognized (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total	$ 20,948	$ 11,349	$ 9,971
Research and Development [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total	7,815	4,530	3,632
General and Administrative [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total	$ 13,133	$ 6,819	$ 6,339

Stockholders' Equity - Assumpti

Stockholders' Equity - Assumptions for Fair Values of Employee Stock Options Granted under Company's Stock Plans (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	0.00%	0.00%	0.00%
Volatility	87.40%	71.30%	67.80%
Weighted-average expected life (in years)	6 years	6 years	6 years
Risk-free interest rate	0.66%	2.28%	2.66%
Weighted-average grant date fair value	$ 35.71	$ 7.54	$ 6.22
ESPP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	0.00%	0.00%	0.00%
Volatility	118.40%	56.40%	73.80%
Weighted-average expected life (in years)	6 months	6 months	6 months
Risk-free interest rate	0.13%	1.87%	2.33%
Weighted-average grant date fair value	$ 25.93	$ 4.10	$ 3.73

Stockholders' Equity - Stock-ba

Stockholders' Equity - Stock-based Compensation Expense in Connection with Grants of Stock Options to Nonemployees (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense associated with stock options granted to nonemployees	$ 1,964	$ 289	$ 862
Research and Development [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense associated with stock options granted to nonemployees	1,892	186	862
General and Administrative [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense associated with stock options granted to nonemployees	$ 72	$ 103	$ 0

Stockholders' Equity - Assump_2

Stockholders' Equity - Assumptions for Fair Values of Stock Options Granted are Calculated Related to Stock Options Granted to Nonemployees (Detail)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	0.00%	0.00%	0.00%
Volatility	87.00%
Weighted-average expected life (in years)	6 years
Risk-free interest rate	0.84%
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility		68.00%	67.00%
Weighted-average expected life (in years)		5 years 6 months	5 years 8 months 12 days
Risk-free interest rate		1.60%	2.70%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Volatility		87.00%	68.00%
Weighted-average expected life (in years)		6 years	9 years 10 months 24 days
Risk-free interest rate		2.20%	3.00%

401 (k) Plan - Additional Infor

401 (k) Plan - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Postemployment Benefits [Abstract]
Matching contributions by employer	$ 0	$ 0	$ 0

Income Taxes - Components of In

Income Taxes - Components of Income Tax (Benefit) Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current (benefit from) provision for income taxes:
Federal	$ 0	$ 0	$ 0
State	0	0	0
Total current (benefit from) provision for income taxes	0	0	0
Deferred (benefit from) provision for income taxes:
Federal	0	0	0
State	0	0	0
Total deferred tax (benefit from) provision for income taxes	0	0	0
(Benefit from) provision for income taxes	$ 0	$ 0	$ 0

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of the Federal Statutory Income Tax Rate to the Company's Effective Income Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Federal statutory income tax rate	(21.00%)	(21.00%)	(21.00%)
Permanent items	2.10%	1.30%	1.60%
Excess tax benefit for stock-based compensation	(40.90%)	(13.30%)	(2.80%)
Tax credits	(13.40%)	(38.30%)	(3.50%)
Change in valuation allowance	70.40%	70.30%	24.50%
Non-deductible executive compensation	2.70%	1.00%	0.60%
Other	0.10%	0.00%	0.60%
(Benefit from) provision for income taxes	0.00%	0.00%	0.00%

Income Taxes - Tax Effects of T

Income Taxes - Tax Effects of Temporary Differences and Carryforwards that Give Rise to Significant Portions of the Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Net operating loss carryforwards	$ 120,347	$ 76,033
Tax credits	49,229	39,625
Amortization of deferred stock compensation - non- qualified	4,165	5,172
Reserves and accruals	1,770	1,528
Deferred revenue	7,684	20,312
Depreciation and amortization	0	15
Lease liability	8,299	434
Gross deferred tax assets	191,494	143,119
Less: valuation allowance	(183,948)	(142,761)
Total deferred tax assets	7,546	358
Deferred tax liabilities:
Property, Plant and Equipment	(1,894)	0
Right of use asset	(5,652)	(358)
Total deferred tax liabilities	(7,546)	(358)
Net deferred tax assets	$ 0	$ 0

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Taxes [Line Items]
Increase (decrease) in valuation allowance	$ 41,200,000	$ 39,900,000
Federal operating loss carryforwards net	489,700,000
State operating loss carryforwards net	$ 225,700,000
Federal operating loss carryforwards expiry	2032
State operating loss carryforwards expiry	2028
Federal research and development credits will begin to expire	2021
Unrecognized tax benefits	$ 30,464,000	29,176,000	$ 9,714,000
Unrecognized tax benefits that would affect the Company's effective tax rate	0	$ 0
Income tax penalties and interest expense, unrecognized tax benefits	0
Federal [Member]
Income Taxes [Line Items]
Research and development credit	14,200,000
State and Local [Member]
Income Taxes [Line Items]
Research and development credit	12,200,000
Orphan Drug [Member]
Income Taxes [Line Items]
Research and development credit	$ 52,600,000
California research and development credits expiration year	2034

Income Taxes - Reconciliation_2

Income Taxes - Reconciliation of the Company's Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Beginning Balance	$ 29,176	$ 9,714
Additions for current tax positions	1,317	3,455
Additions for prior tax positions		16,007
Releases	(29)
Ending Balance	$ 30,464	$ 29,176

Selected Quarterly Financial _3

Selected Quarterly Financial Data - Selected Quarterly Results from Operations (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 4,358	$ 5,085	$ 49,440	$ 6,008	$ 10,047	$ 10,581	$ 7,173	$ 8,327	$ 64,891	$ 36,128	$ 42,875
Net income (loss)	$ (29,876)	$ (24,060)	$ 20,267	$ (21,687)	$ (15,528)	$ (12,862)	$ (15,150)	$ (11,949)	$ (55,356)	$ (55,489)	$ (37,966)
Basic net income (loss) per share	$ (0.43)	$ (0.35)	$ 0.32	$ (0.35)
Diluted net income (loss) per share	$ (0.43)	$ (0.35)	$ 0.29	$ (0.35)
Basic and diluted net loss per common share					$ (0.26)	$ (0.22)	$ (0.26)	$ (0.23)	$ (0.84)	$ (0.98)	$ (0.76)

Subsequent Event - Additional I

Subsequent Event - Additional Information (Detail) $ in Millions	Feb. 28, 2021USD ($)
Vifor [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Regulatory milestone	$ 10