Earnings (Loss) Per Share - Calculation of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
BASIC
Net income (loss)	$ 2,669	$ (5,061)	$ (1,005)	$ 959	$ 22,659	$ (587)	$ (3,397)	$ 23,031
Weighted-average common shares outstanding (in shares)	13,894			13,836			13,861	13,997
Basic earnings (loss) per share (in dollars per share)	$ 0.19			$ 0.07			$ (0.25)	$ 1.65
DILUTED
Net income (loss)	$ 2,669	$ (5,061)	$ (1,005)	$ 959	$ 22,659	$ (587)	$ (3,397)	$ 23,031
Weighted-average common shares outstanding (in shares)	13,894			13,836			13,861	13,997
Dilutive effect of stock options, restricted stock and common stock warrants (in shares)	276			123			0	119
Weighted-average common shares outstanding on a diluted basis (in shares)	14,170			13,959			13,861	14,116
Diluted earnings (loss) per share (in dollars per share)	$ 0.19			$ 0.07			$ (0.25)	$ 1.63