LOANS RECEIVABLE AND ALLOWANCE FOR LOAN LOSSES - Non-accrual loans (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Financing Receivable Nonaccrual Status [Roll Forward]
Balance	$ 4,512	$ 4,127
Transfer into non-accrual	1,196	2,117
Loans paid down/payoffs	(2,088)	(409)
Loans return to accrual status	(650)	(594)
Loans charged off	(189)	(277)
Balance	2,781	4,964
Real Estate Loan
Financing Receivable Nonaccrual Status [Roll Forward]
Balance	4,299
Balance	2,584
Commercial and Industrial
Financing Receivable Nonaccrual Status [Roll Forward]
Balance	71
Consumer Loans
Financing Receivable Nonaccrual Status [Roll Forward]
Balance	213
Single-family | Real Estate Loan
Financing Receivable Nonaccrual Status [Roll Forward]
Balance	270	790
Transfer into non-accrual		64
Loans paid down/payoffs	(138)	(239)
Balance	132	615
Multi-family | Real Estate Loan
Financing Receivable Nonaccrual Status [Roll Forward]
Balance		24
Loans paid down/payoffs		(16)
Balance		8
Commercial | Real Estate Loan
Financing Receivable Nonaccrual Status [Roll Forward]
Balance	4,029	3,139
Transfer into non-accrual	920	1,619
Loans paid down/payoffs	(1,881)	(100)
Loans return to accrual status	(616)	(577)
Balance	2,452	4,081
Commercial | Consumer Loans
Financing Receivable Nonaccrual Status [Roll Forward]
Balance	126
SBA Guaranty | Commercial and Industrial
Financing Receivable Nonaccrual Status [Roll Forward]
Transfer into non-accrual	71
Balance	71
Consumer and Indirect | Consumer Loans
Financing Receivable Nonaccrual Status [Roll Forward]
Balance	34	51
Transfer into non-accrual	1
Loans paid down/payoffs	(1)	(7)
Loans return to accrual status	(34)
Balance		44
Automobile | Consumer Loans
Financing Receivable Nonaccrual Status [Roll Forward]
Balance	179	123
Transfer into non-accrual	204	434
Loans paid down/payoffs	(68)	(47)
Loans return to accrual status		(17)
Loans charged off	(189)	(277)
Balance	$ 126	$ 216