Earnings Per Share - Computation of Basic and Diluted Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Net income (loss) available to common shareholders	$ (57,955)	$ 49,006	$ (99,250)
Weighted average common shares outstanding - Basic (in shares)	40,253	39,556	39,244
Dilutive effect of stock-based awards (in shares)	0	424	0
Weighted average common shares outstanding - Diluted (in shares)	40,253	39,980	39,244
Earnings (loss) per common share - Basic (in dollars per share)	$ (1.44)	$ 1.24	$ (2.53)
Earnings (loss) per common share - Diluted (in dollars per share)	$ (1.44)	$ 1.23	$ (2.53)