Earnings (Loss) Per Share - Earning per share basic and diluted (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
Numerator:
Net earnings (loss)	$ (5,869)	$ 6,585	$ (13,590)	$ 12,067
Denominator:
Basic weighted average shares outstanding (in shares)	9,756	9,912	9,760	9,933
Effect of dilutive securities:
Employee share-based awards (in shares)		17		63
Diluted weighted average shares outstanding (in shares)	9,756	9,929	9,760	9,996
Basic earnings (loss) per share	$ (0.60)	$ 0.66	$ (1.39)	$ 1.21
Diluted earnings (loss) per share	$ (0.60)	$ 0.66	$ (1.39)	$ 1.21