BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Loans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Mar. 11, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unamortized retained loan discounts	$ 9,400		$ 9,400		$ 7,800
Loan receivable, nonaccrual, past due period (more than)			60 days
Loans receivable, impairment and (recovery) recorded	7	$ 1	$ 11	$ (15)
Loan loss reserves	959		959		885
PMC Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Acquisition discounts at acquisition date						$ 33,900
Acquisition discount	$ 420		$ 420		$ 492