Income (Loss) per Share - Basic and Diluted Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Jul. 14, 2016
Earnings Per Share Reconciliation [Abstract]
Net income (loss)	$ 7,006	$ (13,088)	$ 34,792	$ (31,761)
Undistributed income allocated to participating securities	92	0	415	0
Numerator for diluted income (loss) per common share	6,914	(13,088)	34,377	(31,761)
Plus: Net income effect of convertible securities	0	0	0	0
Numerator for diluted income (loss) per common share	$ 6,914	$ (13,088)	$ 34,377	$ (31,761)
Basic weighted-average common stock shares outstanding (in shares)	45,541	41,015	45,505	40,991
Dilutive effects of common stock equivalents (in shares)	23	0	31	0
Diluted weighted-average common stock shares outstanding (in shares)	45,564	41,015	45,536	40,991
Basic income (loss) per share (USD per share)	$ 0.15	$ (0.32)	$ 0.76	$ (0.77)
Diluted income (loss) per share (USD per share)	$ 0.15	$ (0.32)	$ 0.75	$ (0.77)
5.00% Convertible Senior Notes due 2021
Earnings Per Share Reconciliation [Abstract]
Debt instrument, interest rate	5.00%		5.00%		5.00%
Warrant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average number of shares issuable under the common stock warrants (in shares)			354	343
Stock Option Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average number of shares issuable under the common stock warrants (in shares)	354	343
Stock Option Awards
Earnings Per Share Reconciliation [Abstract]
Antidilutive securities excluded from computation of earnings per share (in shares)	1,500	1,000	1,500	800
Restricted Stock Awards
Earnings Per Share Reconciliation [Abstract]
Antidilutive securities excluded from computation of earnings per share (in shares)	98	443	101	440
Convertible debt securities
Earnings Per Share Reconciliation [Abstract]
Antidilutive securities excluded from computation of earnings per share (in shares)	6,400	583	6,400	292