FAIR VALUE - Summary of assets measured at level 3 fair value on recurring basis (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2022 USD ($) loan	Dec. 31, 2021 USD ($) loan
Summary of assets measured on a recurring and nonrecurring basis
Impaired Financing Receivable, with Related Allowance, Recorded Investment	$ 2,192	$ 2,192
Loans and Leases Receivable, Allowance	13,885	13,732
Net recorded investment	$ 2,524	$ 2,564
Cash, Securities and Other
Summary of assets measured on a recurring and nonrecurring basis
Loan Reserved For Specific Allowance | loan	1	1
Impaired Financing Receivable, with Related Allowance, Recorded Investment	$ 2	$ 2
Level 3
Summary of assets measured on a recurring and nonrecurring basis
Impaired Financing Receivable, with Related Allowance, Recorded Investment	2,200
Loans and Leases Receivable, Allowance	1,800
Provision for loan losses	1,800	1,800
Commercial and Industrial | Nonrecurring
Summary of assets measured on a recurring and nonrecurring basis
Net recorded investment	439	439
Commercial and Industrial | Level 3 | Nonrecurring
Summary of assets measured on a recurring and nonrecurring basis
Net recorded investment	$ 439	$ 439