CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Statement [Abstract]
Revenue	$ 28,650	$ 67	$ 29,156	$ 425
Operating expenses:
Research and development	2,754	6,745	10,684	18,252
General and administrative	6,366	2,681	11,984	7,531
Total operating expenses	9,120	9,426	22,668	25,783
Income (loss) from operations	19,530	(9,359)	6,488	(25,358)
Other income (expense):
Other income (loss), net	(43)	73	96	3,207
Loss on extinguishment of debt	0	0	(915)	0
Interest expense	0	(407)	(247)	(972)
Total other income (expense), net	(43)	(334)	(1,066)	2,235
Net income (loss) and comprehensive income (loss)	$ 19,487	$ (9,693)	$ 5,422	$ (23,123)
Net income (loss) per share — basic (in dollars per share)	$ 0.95	$ (0.50)	$ 0.27	$ (1.23)
Weighted-average number of common shares used in net income (loss) per share — basic (in shares)	20,495	19,345	20,004	18,806
Net income (loss) per share — diluted (in dollars per share)	$ 0.91	$ (0.50)	$ 0.26	$ (1.23)
Weighted-average number of common shares used in net income (loss) per share — diluted (in shares)	21,423	19,345	20,796	18,806