Condensed Statements of Operations and Comprehensive Income (Loss) (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Revenue:
Licensing revenue	$ 4,767	$ 1,989	$ 14,509	$ 5,967
Collaborative development revenue	2,831	4,604	10,775	14,473
Total revenue	7,598	6,593	25,284	20,440
Operating expenses:
Research and development	5,694	6,584	18,514	19,757
General and administrative	1,823	895	4,401	2,830
Total operating expenses	7,517	7,479	22,915	22,587
Income (loss) from operations	81	(886)	2,369	(2,147)
Other expense, net	(7)	(13)	(19)	(42)
Change in fair value of preferred stock warrant liability			(1,593)
Income (loss) before provision for income taxes	74	(899)	757	(2,189)
Provision for income taxes		35		106
Net income (loss) and comprehensive income (loss)	74	(934)	757	(2,295)
Net income (loss) attributable to common stockholders:
Basic	74	(934)		(2,295)
Diluted	$ 74	$ (934)		$ (2,295)
Shares used to compute net income (loss) per share attributable to common stockholders:
Basic	18,374,277	1,156,446	7,476,642	1,100,885
Diluted	19,133,217	1,156,446	7,476,642	1,100,885
Net income (loss) per share attributable to common stockholders:
Basic		$ (0.81)		$ (2.08)
Diluted		$ (0.81)		$ (2.08)