Condensed Consolidated Statements of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit	Total
Beginning Balances at Dec. 31, 2020	$ 7	$ 1,043,991	$ (270)	$ (762,754)	$ 280,974
Beginning Balances (in shares) at Dec. 31, 2020	72,513,348
Net loss				(172,947)	(172,947)
Issuance of common stock upon exercise of stock options		4,429			4,429
Issuance of common stock upon exercise of stock options (in shares)	451,883
Issuance of common stock upon vesting of RSUs (in shares)	252,846
Stock-based compensation expense		16,982			16,982
Taxes paid related to net share settlement of RSUs		(1,730)			(1,730)
Taxes paid related to net share settlement of RSUs (in shares)	(95,169)
Other comprehensive gain (loss), net of tax			(37)		(37)
Ending Balances at Mar. 31, 2021	$ 7	1,063,672	(307)	(935,701)	127,671
Ending Balances (in shares) at Mar. 31, 2021	73,122,908
Beginning Balances at Dec. 31, 2020	$ 7	1,043,991	(270)	(762,754)	280,974
Beginning Balances (in shares) at Dec. 31, 2020	72,513,348
Net loss					(241,375)
Ending Balances at Sep. 30, 2021	$ 7	1,135,155	(273)	(1,004,129)	130,760
Ending Balances (in shares) at Sep. 30, 2021	76,583,279
Beginning Balances at Mar. 31, 2021	$ 7	1,063,672	(307)	(935,701)	127,671
Beginning Balances (in shares) at Mar. 31, 2021	73,122,908
Net loss				(29,900)	(29,900)
Issuance of common stock upon exercise of stock options		4,009			4,009
Issuance of common stock upon exercise of stock options (in shares)	686,145
Issuance of common stock upon vesting of RSUs (in shares)	9,334
Stock-based compensation expense		11,512			11,512
Issuance of common stock to Shanghai Junshi Biosciences Ltd. ("Junshi Biosciences"), net of issuance costs		40,903			40,903
Issuance of common stock to Shanghai Junshi Biosciences Ltd. ("Junshi Biosciences"), net of issuance costs (in shares)	2,491,988
Issuance of common stock under the ESPP		1,985			1,985
Issuance of common stock under the ESPP (in shares)	154,325
Other comprehensive gain (loss), net of tax			40		40
Ending Balances at Jun. 30, 2021	$ 7	1,122,081	(267)	(965,601)	156,220
Ending Balances (in shares) at Jun. 30, 2021	76,464,700
Net loss				(38,528)	(38,528)
Issuance of common stock upon exercise of stock options		1,288			1,288
Issuance of common stock upon exercise of stock options (in shares)	116,246
Issuance of common stock upon vesting of RSUs (in shares)	2,333
Stock-based compensation expense		11,786			11,786
Other comprehensive gain (loss), net of tax			(6)		(6)
Ending Balances at Sep. 30, 2021	$ 7	1,135,155	(273)	(1,004,129)	130,760
Ending Balances (in shares) at Sep. 30, 2021	76,583,279
Beginning Balances at Dec. 31, 2021	$ 7	1,147,843	(270)	(1,049,854)	$ 97,726
Beginning Balances (in shares) at Dec. 31, 2021	76,930,096				76,930,096
Net loss				(96,084)	$ (96,084)
Issuance of common stock upon exercise of stock options		544			544
Issuance of common stock upon exercise of stock options (in shares)	102,632
Issuance of common stock upon vesting of RSUs (in shares)	491,087
Stock-based compensation expense		13,037			13,037
Taxes paid related to net share settlement of RSUs		(2,658)			(2,658)
Taxes paid related to net share settlement of RSUs (in shares)	(185,644)
Other comprehensive gain (loss), net of tax			(2)		(2)
Ending Balances at Mar. 31, 2022	$ 7	1,158,766	(272)	(1,145,938)	12,563
Ending Balances (in shares) at Mar. 31, 2022	77,338,171
Beginning Balances at Dec. 31, 2021	$ 7	1,147,843	(270)	(1,049,854)	$ 97,726
Beginning Balances (in shares) at Dec. 31, 2021	76,930,096				76,930,096
Net loss					$ (232,884)
Ending Balances at Sep. 30, 2022	$ 7	1,185,868	(270)	(1,282,738)	$ (97,133)
Ending Balances (in shares) at Sep. 30, 2022	77,770,593				77,770,593
Beginning Balances at Mar. 31, 2022	$ 7	1,158,766	(272)	(1,145,938)	$ 12,563
Beginning Balances (in shares) at Mar. 31, 2022	77,338,171
Net loss				(50,150)	(50,150)
Issuance of common stock upon exercise of stock options		8			8
Issuance of common stock upon exercise of stock options (in shares)	4,499
Issuance of common stock upon vesting of RSUs (in shares)	173,867
Stock-based compensation expense		13,935			13,935
Issuance of common stock under the ESPP		1,655			1,655
Issuance of common stock under the ESPP (in shares)	244,983
Taxes paid related to net share settlement of RSUs		(642)			(642)
Taxes paid related to net share settlement of RSUs (in shares)	(58,771)
Other comprehensive gain (loss), net of tax			2		2
Ending Balances at Jun. 30, 2022	$ 7	1,173,722	(270)	(1,196,088)	(22,629)
Ending Balances (in shares) at Jun. 30, 2022	77,702,749
Net loss				(86,650)	(86,650)
Issuance of common stock upon exercise of stock options		79			79
Issuance of common stock upon exercise of stock options (in shares)	6,557
Issuance of common stock upon vesting of RSUs (in shares)	93,606
Stock-based compensation expense		12,388			12,388
Taxes paid related to net share settlement of RSUs		(321)			(321)
Taxes paid related to net share settlement of RSUs (in shares)	(32,319)
Ending Balances at Sep. 30, 2022	$ 7	$ 1,185,868	$ (270)	$ (1,282,738)	$ (97,133)
Ending Balances (in shares) at Sep. 30, 2022	77,770,593				77,770,593