FAIR VALUE OF ASSETS AND LIABILITIES - Impaired Loans (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Assets and liabilities measured on non-recurring basis
Total Losses	$ 5,132,000	$ 749,000	$ 7,972,000	$ 3,081,000
Residential loans
Assets and liabilities measured on non-recurring basis
Total Losses		103,000		369,000
Commercial real estate
Assets and liabilities measured on non-recurring basis
Total Losses	5,124,000		5,124,000
Commercial and industrial
Assets and liabilities measured on non-recurring basis
Total Losses	8,000	644,000	2,824,000	2,654,000
Other real estate owned and repossessed assets
Assets and liabilities measured on non-recurring basis
Total Losses		$ 2,000	24,000	$ 58,000
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	23,492,000		23,492,000		8,756,000
Non-recurring | Level 3 | Residential loans
Assets and liabilities measured on non-recurring basis
Fair value	846,000		846,000		919,000
Non-recurring | Level 3 | Commercial real estate
Assets and liabilities measured on non-recurring basis
Fair value	17,662,000		17,662,000		3,034,000
Non-recurring | Level 3 | Commercial and industrial
Assets and liabilities measured on non-recurring basis
Fair value	4,956,000		4,956,000		4,208,000
Non-recurring | Level 3 | Other real estate owned and repossessed assets
Assets and liabilities measured on non-recurring basis
Fair value	$ 28,000		$ 28,000		$ 595,000