LOANS AND ALLOWANCE FOR CREDIT LOSSES - Summary of Amortized Cost Basis of Collateral-dependent Loans (Details) - Collateral Dependent Loans - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Financing Receivable Allowance For Credit Losses [Line Items]
Amortized cost	$ 5,268	$ 10,727
Allowance for Credit Losses Allocation	850	2,300
Real Estate
Financing Receivable Allowance For Credit Losses [Line Items]
Amortized cost	5,268	10,727
Commercial and industrial
Financing Receivable Allowance For Credit Losses [Line Items]
Amortized cost	119	129
Allowance for Credit Losses Allocation	40	44
Commercial and industrial | Real Estate
Financing Receivable Allowance For Credit Losses [Line Items]
Amortized cost	119	129
Construction and development
Financing Receivable Allowance For Credit Losses [Line Items]
Amortized cost	609	609
Allowance for Credit Losses Allocation	207	208
Construction and development | Real Estate
Financing Receivable Allowance For Credit Losses [Line Items]
Amortized cost	609	609
Commercial real estate
Financing Receivable Allowance For Credit Losses [Line Items]
Amortized cost	4,540	9,989
Allowance for Credit Losses Allocation	603	2,048
Commercial real estate | Real Estate
Financing Receivable Allowance For Credit Losses [Line Items]
Amortized cost	$ 4,540	$ 9,989