Net Loss Per Common Share - Calculation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Numerator:
Net loss and comprehensive loss	$ (58,029)	$ (15,719)	$ (87,748)	$ (36,555)
Denominator:
Weighted-average basic and diluted common shares (in shares)	27,971,733	23,013,838	27,850,199	19,876,850
Basic and diluted net loss per common share (in dollars per share)	$ (2.07)	$ (0.68)	$ (3.15)	$ (1.84)