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, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share Reconciliation [Abstract]
Net Income (Loss)	$ (14,271)	$ (40,560)	$ (222,337)	$ (83,891)	$ 28,169	$ 61,092	$ (277,168)	$ 5,370
Less: Undistributed income allocated to participating securities	0			0			0	59
Net income (loss) attributable to common stockholders	(14,271)			(83,891)			(277,168)	5,311
Plus: Net income effect of convertible securities	0			0			0	0
Numerator for diluted income (loss) per common share	$ (14,271)			$ (83,891)			$ (277,168)	$ 5,311
Basic weighted-average common stock shares outstanding (in shares)	53,374			50,942			53,265	49,973
Dilutive effects of common stock equivalents (in shares)	0			0			0	98
Diluted weighted-average common stock shares outstanding (in shares)	53,374			50,942			53,265	50,071
Basic income (loss) per share (in dollars per share)	$ (0.27)			$ (1.65)			$ (5.20)	$ 0.11
Diluted income (loss) per share (in dollars per share)	$ (0.27)			$ (1.65)			$ (5.20)	$ 0.11
5.00% Convertible Senior Notes due 2021
Earnings Per Share Reconciliation [Abstract]
Debt instrument, interest rate	5.00%						5.00%
Restricted Stock Awards
Earnings Per Share Reconciliation [Abstract]
Antidilutive securities excluded from computation of earnings per share (in shares)								160
Stock Option Awards
Earnings Per Share Reconciliation [Abstract]
Antidilutive securities excluded from computation of earnings per share (in shares)								1,800
Convertible Debt Securities
Earnings Per Share Reconciliation [Abstract]
Antidilutive securities excluded from computation of earnings per share (in shares)								5,500
Convertible Debt Securities | 5.00% Convertible Senior Notes due 2021
Earnings Per Share Reconciliation [Abstract]
Debt instrument, interest rate	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			82	354