Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Operating expenses:
Research and development	$ (31,985)	$ (12,554)
General and administrative	(9,894)	(7,842)
Loss from operations	(41,879)	(20,396)
Interest expense	(1,418)	(1,230)
Interest income	443	89
Loss on extinguishment of debt		(4,399)
Change in fair value of warrant liabilities		267
Change in fair value of Convertible Bridge Notes redemption rights derivative		480
Change in fair value of 2020 Convertible Notes derivative liability		(42,793)
Net loss	$ (42,854)	$ (67,982)
Net loss per share attributable to common stockholders—basic and diluted	$ (1.60)	$ (3.72)
Weighted-average number of shares outstanding—basic and diluted	26,735,175	18,311,333