Computation of Earnings per Share - Net loss per share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Computation of Earnings per Share
Net income (loss)	$ (1,060)	$ 228
Shares outstanding:
Weighted-average common shares outstanding (in shares)	21,522	21,565
Additional dilutive common stock equivalents (in shares)		17
Diluted shares outstanding (in shares)	21,522	21,582
Net income (loss) per share - basic (in dollars per share)	$ (0.05)	$ 0.01
Net income (loss) per share - diluted (in dollars per share)	$ (0.05)	$ 0.01