Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Operating expenses:
General and administrative	$ 8,809	$ 3,867	$ 22,212	$ 11,296
Research and development	51,924	32,092	156,033	83,387
Totals	60,733	35,959	178,245	94,683
Loss from operations	(60,733)	(35,959)	(178,245)	(94,683)
Other income (expenses):
Interest income	318	111	654	223
Other income (expense)	(2)	4	26	(22)
Totals	316	115	680	201
Net loss	(60,417)	(35,844)	(177,565)	(94,482)
Net loss applicable to common stock	$ (60,417)	$ (35,844)	$ (177,565)	$ (94,482)
Net loss per common share—basic and diluted	$ (1.87)	$ (1.19)	$ (5.55)	$ (3.16)
Weighted-average common shares outstanding—basic and diluted	32,303,203	30,117,819	32,018,869	29,936,254