FAIR VALUE - Loans measured at fair value under fair value option (Details) - USD ($)	Mar. 31, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total loans, fair value	$ 40,043,000	$ 30,620,000
Total loans, unpaid principal balance	40,081,000	29,857,000
Total loans, difference	(38,000)	763,000
Non-accruals, fair value	0	0
90 days or more past due, fair value	0	0
Loans Held for Sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total loans, fair value	33,663,000	30,620,000
Total loans, unpaid principal balance	33,713,000	29,857,000
Total loans, difference	(50,000)	$ 763,000
Loan Held for Investment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total loans, fair value	6,380,000
Total loans, unpaid principal balance	6,368,000
Total loans, difference	$ 12,000