Net Loss Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Basic and diluted net loss per common share calculation:
Net loss	$ (43,122)	$ (36,301)
Weighted average common shares outstanding - basic and diluted (in shares)	35,804	35,256
Net loss per share of common stock - basic and diluted (in dollars per share)	$ (1.20)	$ (1.03)
Anti-dilutive securities
Total (in shares)	4,677	3,899
Stock options outstanding
Anti-dilutive securities
Total (in shares)	3,999	3,495
Restricted stock units
Anti-dilutive securities
Total (in shares)	678	404