LOANS RECEIVABLE AND ALLOWANCE FOR LOAN LOSSES - Troubled debt restructured loans (Details) - USD ($)	Sep. 30, 2021	Dec. 31, 2020
Financing Receivable, Impaired [Line Items]
Troubled debt restructured loans	$ 37,000	$ 39,000
Non-accrual and 90+ days past due and still accruing loans to average loans	1.17%	1.63%
Allowance for credit losses to non-accrual and 90 days or more and still accruing loans	99.60%	32.60%
Consumer and Indirect
Financing Receivable, Impaired [Line Items]
Troubled debt restructured loans	$ 36,532