Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Operating expenses:
Research and development	$ 45,200	$ 23,581
General and administrative	12,280	7,133
Total operating expenses	57,480	30,714
Loss from operations	(57,480)	(30,714)
Interest income, net	707	175
Other expense, net	(5)	(4)
Net loss	$ (56,778)	$ (30,543)
Net loss per share—basic and diluted	$ (1.52)	$ (0.97)
Weighted average common shares outstanding—basic and diluted	37,269,148	31,643,216
Comprehensive loss:
Net loss	$ (56,778)	$ (30,543)
Other comprehensive items:
Unrealized gain on marketable securities	21
Total other comprehensive gain	21
Total comprehensive loss	$ (56,757)	$ (30,543)