SHAREHOLDERS' EQUITY - Share Buyback (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Sep. 12, 2019	Sep. 05, 2017
Equity, Class of Treasury Stock [Line Items]
Treasury stock, value acquired, cost method		$ 12,077,000	$ 7,518,000
New share repurchase program
Equity, Class of Treasury Stock [Line Items]
Authorized amount under the share repurchase program				$ 5,000,000	$ 5,000,000
Treasury stock, shares acquired (in shares)	17,364	39,093
Treasury stock acquired, average cost per share (in dollars per share)	$ 11.95	$ 15.76
Treasury stock, value acquired, cost method	$ 207,000	$ 616,000
Remaining authorized repurchase amount		$ 4,384,000