Income (Loss) Per Share - Commutation of Basic and Diluted Loss per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share [Abstract]
Net loss	$ 13,687	$ (27,761)	$ (13,088)	$ (18,673)	$ (66,836)	$ 14,740	$ 11,723	$ 462	$ (45,835)	$ (39,911)	$ (47,041)
Undistributed income allocated to participating securities									0	0	0
Net income (loss) attributable to common stockholders									$ (45,835)	$ (39,911)	$ (47,041)
Basic weighted-average common stock shares outstanding (in shares)									42,349	37,678	32,739
Add dilutive effects of common stock equivalents (in shares)									0	0	0
Diluted weighted-average common stock shares outstanding (in shares)									42,349	37,678	32,739
Basic and diluted loss per common share (in USD per share)									$ (1.08)	$ (1.06)	$ (1.44)