Income (Loss) per Share - Basic and Diluted Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Jul. 14, 2016
Earnings Per Share Reconciliation [Abstract]
Net income (loss)	$ 18,824	$ (27,761)	$ 53,616	$ (59,522)
Undistributed income allocated to participating securities	238	0	685	0
Net income (loss) attributable to common stockholders	18,586	(27,761)	52,931	(59,522)
Plus: Net income effect of convertible securities	2,566	0	0	0
Numerator for diluted income (loss) per common share	$ 21,152	$ (27,761)	$ 52,931	$ (59,522)
Basic weighted-average common stock shares outstanding (in shares)	45,561	41,580	45,505	41,309
Dilutive effects of common stock equivalents (in shares)	6,431	0	22	0
Diluted weighted-average common stock shares outstanding (in shares)	51,992	41,580	45,527	41,309
Basic income (loss) per share (USD per share)	$ 0.41	$ (0.67)	$ 1.16	$ (1.44)
Diluted income (loss) per share (USD per share)	$ 0.41	$ (0.67)	$ 1.16	$ (1.44)
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	352	354	352
Restricted Stock Awards
Earnings Per Share Reconciliation [Abstract]
Antidilutive securities excluded from computation of earnings per share (in shares)	31	463	83	448
Stock Option Awards
Earnings Per Share Reconciliation [Abstract]
Antidilutive securities excluded from computation of earnings per share (in shares)	1,300	1,700	1,500	1,700
Convertible Debt Securities
Earnings Per Share Reconciliation [Abstract]
Antidilutive securities excluded from computation of earnings per share (in shares)		6,400	6,400	2,300