Statements of Operations (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Collaboration and license revenue	$ 10,531	$ 72,042	$ 78,029
Operating expenses:
Research and development	79,286	49,717	46,089
General and administrative	15,423	11,469	12,071
Total operating expenses	94,709	61,186	58,160
Income (loss) from operations	(84,178)	10,856	19,869
Interest and other income, net	826	510	136
Interest expense			(21)
Net income (loss)	(83,352)	11,366	19,984
Net income (loss) attributable to common stockholders:
Basic	(83,352)		79
Diluted	$ (83,352)		$ 127
Net income (loss) per share attributable to common stockholders:
Basic	$ (3.65)		$ 0.06
Diluted	$ (3.65)		$ 0.06
Shares used to compute net income (loss) per share attributable to common stockholders:
Basic	22,842,443	1,350,939	1,249,778
Diluted	22,842,443	2,048,867	2,089,206