BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Loans Receivable (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unamortized retained loan discounts	$ 7,800	$ 7,600
Loan receivable, nonaccrual, past due period (more than)	60 days
Impairment (recovery) on loans receivable	$ (16)	66	$ 147
Loan loss reserves	885	598
PMC Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Acquisition discounts	$ 492	$ 624