SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Summary of basic and diluted earnings per share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
BASIS OF PRESENTATION AND ACCOUNTING POLICIES
Net income	$ 11,837	$ 10,227
Weighted-average common shares outstanding	5,841	5,784
Basic and diluted earnings per share	$ 2.03	$ 1.77