FAIR VALUE OF ASSETS AND LIABILITIES - Impaired Loans (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Assets and liabilities measured on non-recurring basis
Total Losses	$ 1,519,000	$ 1,033,000	$ 2,901,000	$ 1,085,000
Residential loans
Assets and liabilities measured on non-recurring basis
Total Losses		584,000	5,000	581,000
Commercial real estate
Assets and liabilities measured on non-recurring basis
Total Losses	42,000		42,000
Commercial loans
Assets and liabilities measured on non-recurring basis
Total Losses	1,475,000	$ 449,000	2,830,000	449,000
Other real estate owned and repossessed assets
Assets and liabilities measured on non-recurring basis
Total Losses	2,000		24,000	$ 55,000
Non-recurring
Assets and liabilities measured on non-recurring basis
Fair value	0		0		$ 0
Non-recurring | Level 3
Assets and liabilities measured on non-recurring basis
Fair value	7,076,000		7,076,000		8,756,000
Non-recurring | Level 3 | Residential loans
Assets and liabilities measured on non-recurring basis
Fair value	273,000		273,000		919,000
Non-recurring | Level 3 | Commercial loans
Assets and liabilities measured on non-recurring basis
Fair value	6,505,000		6,505,000		7,242,000
Non-recurring | Level 3 | Other real estate owned and repossessed assets
Assets and liabilities measured on non-recurring basis
Fair value	$ 298,000		$ 298,000		$ 595,000