Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Operating expenses
Selling, general and administrative	$ 17,153	$ 9,386	$ 31,628	$ 19,187
Research and development	10,615	13,304	21,569	25,613
Total operating expenses	27,768	22,690	53,197	44,800
Loss from operations	(27,768)	(22,690)	(53,197)	(44,800)
Other income (expense), net	(618)	(482)	(930)	(1,030)
Net loss before income taxes	(28,386)	(23,172)	(54,127)	(45,830)
Income tax expense	47	47	93	93
Net loss	$ (28,433)	$ (23,219)	$ (54,220)	$ (45,923)
Net loss per share attributable to common stockholders—basic and diluted (in dollars per share)	$ (0.82)	$ (0.87)	$ (1.58)	$ (1.72)
Weighted average number of common shares outstanding—basic and diluted (in shares)	34,783,195	26,773,337	34,283,073	26,748,301
Net loss	$ (28,433)	$ (23,219)	$ (54,220)	$ (45,923)
Net Income (Loss) Attributable to Parent	(28,433)	(23,219)	(54,220)	(45,923)
Unrealized gain (loss) on available-for-sale investments	24	58	(13)	169
Comprehensive loss	$ (28,409)	$ (23,161)	$ (54,233)	$ (45,754)