EARNINGS PER SHARE - Schedule of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Numerator:
Net earnings (basic)	$ 27,402	$ 26,279	$ 20,596
Net earnings (diluted)	$ 27,402	$ 26,279	$ 20,596
Denominator:
Weighted-average shares outstanding (basic) (in shares)	11,108,564	11,638,897	11,562,826
Effect of dilutive securities:
Common stock equivalent shares from stock options (in shares)	32,781	66,202	90,940
Weighted-average shares outstanding (diluted) (in shares)	11,141,345	11,705,099	11,653,766
Net earnings per share
Basic (in USD per share)	$ 2.47	$ 2.26	$ 1.78
Diluted (in USD per share)	$ 2.46	$ 2.25	$ 1.77