FAIR VALUE - Assets Measured at Fair Value on a Nonrecurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage servicing rights, net of valuation allowance	$ 4,300
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	5,539	$ 6,765
Other real estate owned	0	0
Total assets	5,539	6,765
Level 1 | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	0	0
Other real estate owned	0	0
Total assets	0	0
Level 2 | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	0	0
Other real estate owned	0	0
Total assets	0	0
Level 3 | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	5,539	6,765
Other real estate owned	0	0
Total assets	5,539	6,765
Commercial and industrial loans | Working capital lines of credit loans | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	133	178
Commercial and industrial loans | Working capital lines of credit loans | Level 1 | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	0	0
Commercial and industrial loans | Working capital lines of credit loans | Level 2 | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	0	0
Commercial and industrial loans | Working capital lines of credit loans | Level 3 | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	133	178
Commercial and industrial loans | Non-working capital loans | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	4,331	4,904
Commercial and industrial loans | Non-working capital loans | Level 1 | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	0	0
Commercial and industrial loans | Non-working capital loans | Level 2 | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	0	0
Commercial and industrial loans | Non-working capital loans | Level 3 | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	4,331	4,904
Commercial real estate and multi-family residential loans | Owner occupied loans | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	710	1,211
Commercial real estate and multi-family residential loans | Owner occupied loans | Level 1 | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	0	0
Commercial real estate and multi-family residential loans | Owner occupied loans | Level 2 | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	0	0
Commercial real estate and multi-family residential loans | Owner occupied loans | Level 3 | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	710	1,211
Agribusiness and Agricultural | Loans Secured By Farmland | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	43	61
Agribusiness and Agricultural | Loans Secured By Farmland | Level 1 | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	0	0
Agribusiness and Agricultural | Loans Secured By Farmland | Level 2 | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	0	0
Agribusiness and Agricultural | Loans Secured By Farmland | Level 3 | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	43	61
Consumer 1-4 family loans | Closed end first mortgage loans | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	322	411
Consumer 1-4 family loans | Closed end first mortgage loans | Level 1 | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	0	0
Consumer 1-4 family loans | Closed end first mortgage loans | Level 2 | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	0	0
Consumer 1-4 family loans | Closed end first mortgage loans | Level 3 | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	$ 322	$ 411