FAIR VALUE MEASUREMENTS - FV of Financial instruments (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
FINANCIAL ASSETS: (Carrying Amount)
Cash and due from banks	$ 9,627	$ 10,251
Interest-bearing deposits in other banks	36,349	473
Time deposits with other banks	247	247
Restricted investment in bank stocks	2,247	4,224
Net loans	696,461	640,727
Accrued interest receivable	4,730	3,405
FINANCIAL LIABILITIES: (Carrying Amount)
Short-term borrowings	23,123	54,663
Long-term borrowings	45,000	55,000
Accrued interest payable	398	606
Fair Value, Measurements, Nonrecurring [Member]
FINANCIAL ASSETS: (Carrying Amount)
Cash and due from banks	9,627	10,251
Interest-bearing deposits in other banks	36,349	473
Time deposits with other banks	247	247
Restricted investment in bank stocks	2,247	4,224
Net loans	696,461	640,727
Mortgage servicing rights	277	283
Accrued interest receivable	4,730	3,405
FINANCIAL LIABILITIES: (Carrying Amount)
Demand, savings and other deposits	719,553	526,564
Time deposits	199,666	235,064
Short-term borrowings	23,123	54,663
Long-term borrowings	45,000	55,000
Accrued interest payable	398	606
OFF-BALANCE SHEET FINANCIAL INSTRUMENTS (Carrying Amount)	0	0
FINANCIAL ASSETS: (Fair Value)
Cash and due from banks	9,627	10,251
Interest-bearing deposits in other banks	36,349	473
Time deposits with other banks	254	250
Restricted investment in bank stocks	2,247	4,224
Net loans	726,242	655,301
Mortgage servicing rights	277	283
Accrued interest receivable	4,730	3,405
FINANCIAL LIABILITIES: (Fair Value)
Demand, savings and other deposits	719,553	526,564
Time deposits	202,469	235,134
Short-term borrowings	23,128	54,655
Long-term borrowings	47,502	55,809
Accrued interest payable	398	606
OFF-BALANCE SHEET FINANCIAL INSTRUMENTS (Fair Value)	0	0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member]
FINANCIAL ASSETS: (Fair Value)
Cash and due from banks	9,627	10,251
Interest-bearing deposits in other banks	0	0
Time deposits with other banks	0	0
Restricted investment in bank stocks	0	0
Net loans	0	0
Mortgage servicing rights	0	0
Accrued interest receivable	0	0
FINANCIAL LIABILITIES: (Fair Value)
Demand, savings and other deposits	0	0
Time deposits	0	0
Short-term borrowings	0	0
Long-term borrowings	0	0
Accrued interest payable	0	0
OFF-BALANCE SHEET FINANCIAL INSTRUMENTS (Fair Value)	0	0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member]
FINANCIAL ASSETS: (Fair Value)
Cash and due from banks	0	0
Interest-bearing deposits in other banks	36,349	473
Time deposits with other banks	254	250
Restricted investment in bank stocks	2,247	4,224
Net loans	0	0
Mortgage servicing rights	0	0
Accrued interest receivable	4,730	3,405
FINANCIAL LIABILITIES: (Fair Value)
Demand, savings and other deposits	719,553	526,564
Time deposits	202,469	235,134
Short-term borrowings	23,128	54,655
Long-term borrowings	47,502	55,809
Accrued interest payable	398	606
OFF-BALANCE SHEET FINANCIAL INSTRUMENTS (Fair Value)	0	0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
FINANCIAL ASSETS: (Fair Value)
Cash and due from banks	0	0
Interest-bearing deposits in other banks	0	0
Time deposits with other banks	0	0
Restricted investment in bank stocks	0	0
Net loans	726,242	655,301
Mortgage servicing rights	277	283
Accrued interest receivable	0	0
FINANCIAL LIABILITIES: (Fair Value)
Demand, savings and other deposits	0	0
Time deposits	0	0
Short-term borrowings	0	0
Long-term borrowings	0	0
Accrued interest payable	0	0
OFF-BALANCE SHEET FINANCIAL INSTRUMENTS (Fair Value)	$ 0	$ 0