Earnings Per Share - Diluted Earnings (Loss) per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Diluted earnings (loss) per share
Net income (loss)	$ 1,785	$ 1,888	$ 4,935	$ 3,948
Weighted average shares outstanding	9,985	9,976	9,985	9,595
Basic earnings per share	$ 0.179	$ 0.189	$ 0.494	$ 0.411
Effect of dilutive securities:
Cash received for the exercise of stock options				$ 12
Less: Treasury stock purchased with assumed proceeds from exercise	6	7	6	6
Diluted weighted average shares and common stock equivalents	10,000	9,997	10,000	9,611
Diluted earnings per share	$ 0.179	$ 0.189	$ 0.494	$ 0.411
Restricted stock plan
Effect of dilutive securities:
Weighted average shares outstanding under options/ restricted stock plans	9	14	9	10
Delmar 2004 Stock Option Plan | Stock options
Effect of dilutive securities:
Weighted average shares outstanding under options/ restricted stock plans		23	10	28
Weighted average exercise price		$ 7.54	$ 9.05	$ 9.55
Cash received for the exercise of stock options		$ 173	$ 91	$ 267
Average market value per share	$ 7.42	$ 7.79	$ 7.34	$ 7.47
Liberty 2004 Stock Option Plan | Stock options
Effect of dilutive securities:
Weighted average shares outstanding under options/ restricted stock plans	12	14	12	12
Weighted average exercise price	$ 3.98	$ 4.01	$ 3.98	$ 4.02
Cash received for the exercise of stock options	$ 48	$ 56	$ 48	$ 48
Average market value per share	$ 7.42	$ 7.79	$ 7.34	$ 7.47