Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revenue:
Collaborative arrangement revenue	$ 109,674	$ 465	$ 111,976	$ 2,431
Total revenues	198,890	13,296	220,753	25,767
Operating expenses:
Research and development	156,308	146,540	310,431	269,180
Selling, general and administrative	68,628	68,631	141,876	128,910
Cost of royalty and other revenue	1,554	613	2,579	1,043
Change in fair value of contingent consideration	(1,655)	214	(4,763)	510
Total operating expenses	224,835	215,998	450,123	399,643
Loss from operations	(25,945)	(202,702)	(229,370)	(373,876)
Interest income, net	2,939	9,387	8,294	19,489
Other income (expense), net	1,551	(2,936)	(2,896)	(6,325)
Loss before income taxes	(21,455)	(196,251)	(223,972)	(360,712)
Income tax (expense) benefit	(10)	469	(104)	484
Net loss	$ (21,465)	$ (195,782)	$ (224,076)	$ (360,228)
Net loss per share - basic and diluted: (in dollars per share)	$ (0.36)	$ (3.55)	$ (3.86)	$ (6.54)
Weighted-average number of common shares used in computing net loss per share - basic and diluted: (in shares)	60,384	55,165	57,987	55,062
Other comprehensive income (loss):
Other comprehensive income (loss), net of tax expense of $0.1 million and $0.8 million for the three months ended June 30, 2020 and 2019, respectively, and $0.1 million and $1.3 million for the six months ended June 30, 2020 and 2019, respectively	$ 399	$ 973	$ (507)	$ 2,808
Comprehensive loss	(21,066)	(194,809)	(224,583)	(357,420)
Service revenue
Revenue:
Revenue	78,357	11,093	95,190	20,304
Royalty and other revenue
Revenue:
Revenue	$ 10,859	$ 1,738	$ 13,587	$ 3,032