FAIR VALUE MEASUREMENTS - Measured on Non-recurring Basis (Details) - Non-recurring - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2021	Dec. 31, 2020
Assets
Liabilities measured at fair value	$ 0	$ 0	$ 0
Level 3
Assets
Individually evaluated loans	9,247,000	9,247,000	8,746,000
Capitalized servicing rights	4,867,000	4,867,000	3,605,000
Premises held for sale	822,000	822,000	962,000
Total	14,936,000	14,936,000	13,313,000
Total Gains (Losses)	720,000	(1,623,000)
Level 3 | Impaired loans
Assets
Total Gains (Losses)	707,000	(501,000)
Level 3 | Capitalized servicing rights
Assets
Total Gains (Losses)	(136,000)	(1,262,000)
Level 3 | Assets held for sale
Assets
Premises held for sale	822,000	822,000	$ 962,000
Total Gains (Losses)	$ 149,000	$ 140,000