FAIR VALUE MEASUREMENTS, Fair Value of Financial Instruments (Details) - USD ($)	Mar. 31, 2021	Dec. 31, 2020
Loans receivable [Abstract]
Mortgage servicing rights	$ 1,463,000	$ 1,242,000
Carrying Amount [Member] | Level 1 [Member]
Financial assets [Abstract]
Cash and cash equivalents	294,429,000	267,177,000
Carrying Amount [Member] | Level 2 [Member]
Financial assets [Abstract]
Certificates of deposit	14,718,000	16,923,000
Loans receivable [Abstract]
Loans held-for-sale	8,406,000	9,190,000
Interest receivable	4,848,000	5,099,000
Financial liabilities [Abstract]
Federal Home Loan Bank advances	5,000,000	5,000,000
Interest payable	64,000	59,000
Carrying Amount [Member] | Level 3 [Member]
Financial assets [Abstract]
Stock in Federal Home Loan Bank and other equity securities	6,480,000	6,480,000
Loans receivable [Abstract]
Net loans	942,404,000	875,830,000
Mortgage servicing rights	1,463,000	1,242,000
Financial liabilities [Abstract]
Deposits	1,607,037,000	1,478,162,000
Fair Value [Member] | Level 1 [Member]
Financial assets [Abstract]
Cash and cash equivalents	294,429,000	267,177,000
Fair Value [Member] | Level 2 [Member]
Financial assets [Abstract]
Certificates of deposit	15,147,000	17,455,000
Loans receivable [Abstract]
Loans held-for-sale	8,467,000	9,522,000
Interest receivable	4,848,000	5,099,000
Financial liabilities [Abstract]
Federal Home Loan Bank advances	4,999,000	4,996,000
Interest payable	64,000	59,000
Fair Value [Member] | Level 3 [Member]
Financial assets [Abstract]
Stock in Federal Home Loan Bank and other equity securities	6,480,000	6,480,000
Loans receivable [Abstract]
Net loans	890,520,000	830,448,000
Mortgage servicing rights	1,463,000	1,242,000
Financial liabilities [Abstract]
Deposits	$ 1,588,013,000	$ 1,457,051,000