Net Income (Loss) per Share - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share [Abstract]
Net (loss) income	$ 10,018	$ 23,917	$ (102,433)	$ 76,950
Less: Net income allocated to unvested participating restricted stock	(329)	(795)	(420)	(2,621)
Net income (loss) available to common stockholders - basic	9,689	23,122	(102,853)	74,329
Dilutive Securities, Effect on Basic Earnings Per Share, Options and Restrictive Stock Units	2	6	0	28
Net income (loss) available to common stockholders - diluted	$ 9,691	$ 23,128	$ (102,853)	$ 74,357
Weighted average outstanding shares of common stock - basic (in shares)	16,221	16,762	16,229	17,095
Dilutive effect of stock options (in shares)	62	293	0	337
Weighted average outstanding shares of common stock - diluted (in shares)	16,283	17,055	16,229	17,432
Net income per common share - basic (USD per share)	$ 0.60	$ 1.38	$ (6.34)	$ 4.35
Net income per common share - diluted (USD per share)	$ 0.60	$ 1.36	$ (6.34)	$ 4.27