Net Loss Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Basic and diluted net loss per common share calculation:
Net loss	$ (60,891)	$ (39,573)	$ (127,137)	$ (70,068)
Weighted average common shares outstanding - basic and diluted (in shares)	35,594	34,782	35,415	34,432
Net loss per share of common stock - basic and diluted (in dollars per share)	$ (1.71)	$ (1.14)	$ (3.59)	$ (2.03)
Anti-dilutive securities
Total (in shares)	4,144	3,509	4,144	3,509
Stock options outstanding
Anti-dilutive securities
Total (in shares)	3,423	3,224	3,423	3,224
Restricted stock units
Anti-dilutive securities
Total (in shares)	721	285	721	285