Net Loss Per Share - Computation of Basic and Diluted Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Basic and diluted:
Net loss	$ (15,880)	$ (5,638)	$ (36,371)	$ (17,846)
Basic:
Weighted-average common shares outstanding, basic (in shares)	42,325	41,962	42,185	38,869
Dilutive effect of stock options	0	0	0	0
Diluted:
Weighted-average common shares outstanding, diluted (in shares)	42,325	41,962	42,185	38,869
Net loss per share:
Basic (in dollars per share)	$ (0.38)	$ (0.13)	$ (0.86)	$ (0.46)
Diluted (in dollars per share)	$ (0.38)	$ (0.13)	$ (0.86)	$ (0.46)