Consolidated Statements of Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues:
Milestones and license fees	$ 19,769	$ 0	$ 2,919
Total revenues	19,769	0	2,919
Operating expenses:
Research and development	81,491	46,425	39,248
General and administrative	32,480	17,986	13,349
Total operating expenses	113,971	64,411	52,597
Loss from operations	(94,202)	(64,411)	(49,678)
Other income:
Gain (loss) on sale/disposal of assets	9	(4)	37
Deferred gain on real estate	3,325	3,226	3,133
Investment income, net	1,928	629	402
Other income, net	11	18	16
Total other income	5,273	3,869	3,588
Net loss	$ (88,929)	$ (60,542)	$ (46,090)
Net loss per common share:
Basic	$ (1.05)	$ (0.81)	$ (0.69)
Diluted	$ (1.05)	$ (0.81)	$ (0.69)
Shares used in the calculation of net loss per common share:
Basic	84,496	74,577	66,989
Diluted	84,496	74,577	66,989
Other comprehensive loss:
Net loss	$ (88,929)	$ (60,542)	$ (46,090)
Net unrealized (losses) gains on available-for-sale securities	(700)	(282)	7
Comprehensive loss	$ (89,629)	$ (60,824)	$ (46,083)