Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Operating expenses
General and administrative	$ (9,801,000)	$ (8,023,000)
Research and development	(12,309,000)	(11,618,000)
Loss from operations	(22,110,000)	(19,641,000)
Other income (expense), net	(548,000)	2,402,000
Net loss before income taxes	(22,658,000)	(17,239,000)
Income tax expense	(46,000)	0
Net loss	(22,704,000)	(17,239,000)
Net loss attributable to common stockholders—basic and diluted	$ (22,704,000)	$ (17,239,000)
Net loss per share attributable to common stockholders—basic and diluted (in USD per share)	$ (0.85)	$ (0.70)
Weighted average number of common shares outstanding—basic and diluted (shares)	26,723,266	24,602,668
Unrealized gain on available-for-sale investments	$ 111,000	$ 49,000
Comprehensive loss	$ (22,593,000)	$ (17,190,000)