FAIR VALUE - Assets and Liabilities Measured on Nonrecurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Assets and Liabilities Measured on Nonrecurring Basis [Abstract]
Unpaid principal value of business lending loans held for sale	$ 800
Valuation allowance	3,560	$ 3,874
Mortgage Servicing Rights [Member]
Assets and Liabilities Measured on Nonrecurring Basis [Abstract]
Valuation allowance	100	200
Significant Unobservable Inputs, Level 3 [Member]
Assets and Liabilities Measured on Nonrecurring Basis [Abstract]
Impaired loans	21,647	25,063
Business loans held for sale	848
Other real estate owned	824	883
Mortgage servicing rights	807	682
Non-recurring [Member]
Assets and Liabilities Measured on Nonrecurring Basis [Abstract]
Impaired loans	21,647	25,063
Business loans held for sale	848	0
Other real estate owned	824	883
Mortgage servicing rights	807	682
Total	24,126	26,628
Non-recurring [Member] | Quoted Prices in Active Markets For Identical Assets, Level 1 [Member]
Assets and Liabilities Measured on Nonrecurring Basis [Abstract]
Impaired loans	0	0
Business loans held for sale	0	0
Other real estate owned	0	0
Mortgage servicing rights	0	0
Total	0	0
Non-recurring [Member] | Significant Observable Inputs, Level 2 [Member]
Assets and Liabilities Measured on Nonrecurring Basis [Abstract]
Impaired loans	0	0
Business loans held for sale	0	0
Other real estate owned	0	0
Mortgage servicing rights	0	0
Total	0	0
Non-recurring [Member] | Significant Unobservable Inputs, Level 3 [Member]
Assets and Liabilities Measured on Nonrecurring Basis [Abstract]
Impaired loans	21,647	25,063
Business loans held for sale	848	0
Other real estate owned	824	883
Mortgage servicing rights	807	682
Total	$ 24,126	$ 26,628