Earnings (Loss) Per Share - Calculation of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
BASIC
Net income (loss)	$ 14,400	$ 5,846	$ (5,061)	$ (1,005)	$ 20,246	$ (6,066)
Weighted-average common shares outstanding (in shares)	13,915		13,863		13,938	13,845
Basic earnings (loss) per share (in dollars per share)	$ 1.03		$ (0.37)		$ 1.45	$ (0.44)
DILUTED
Net income (loss)	$ 14,400	$ 5,846	$ (5,061)	$ (1,005)	$ 20,246	$ (6,066)
Weighted-average common shares outstanding (in shares)	13,915		13,863		13,938	13,845
Dilutive effect of stock options, restricted stock and common stock warrants (in shares)	236		0		243	0
Weighted-average common shares outstanding on a diluted basis (in shares)	14,151		13,863		14,181	13,845
Diluted earnings (loss) per share (in dollars per share)	$ 1.02		$ (0.37)		$ 1.43	$ (0.44)