Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenues:
License revenue	$ 2,500		$ 13,070
Collaboration revenue	5,211	$ 1,552	18,189	$ 4,603
Total revenues	7,711	1,552	31,259	4,603
Operating expenses:
Research and development	61,545	63,971	180,464	147,642
General and administrative	22,982	14,623	64,463	48,941
Cost of license revenue	1,100		1,520
Change in fair value of contingent consideration	(258)	1,098	205	3,515
Total operating expenses	85,369	79,692	246,652	200,098
Loss from operations	(77,658)	(78,140)	(215,393)	(195,495)
Interest (expense) income, net	(1,155)	937	(1,842)	2,871
Other (expense) income, net	8		(1,180)	(68)
Loss before income taxes	(78,805)	(77,203)	(218,415)	(192,692)
Income tax benefit		178		549
Net loss	$ (78,805)	$ (77,025)	$ (218,415)	$ (192,143)
Net loss per share - basic and diluted:	$ (1.73)	$ (2.07)	$ (5.14)	$ (5.19)
Weighted-average number of common shares used in computing net loss per share - basic and diluted:	45,648	37,201	42,524	37,026
Other comprehensive (loss) income:
Unrealized (loss) gain on available-for-sale securities, net of tax (benefit) expense of $0.0 million for the three and nine months ended September 30, 2017 and $(0.1) and $0.8 million for the three and nine months ended September 30, 2016, respectively	$ (683)	$ (194)	$ (949)	$ 1,455
Comprehensive loss	$ (79,488)	$ (77,219)	$ (219,364)	$ (190,688)