MORTGAGE SERVICING RIGHTS (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)
OTHER INTANGIBLE ASSETS
Income generated as a result of new mortgage servicing rights reported as gains on sale of loans			$ 4,469	$ 9,971
Mortgage Servicing Rights
OTHER INTANGIBLE ASSETS
Income generated as a result of new mortgage servicing rights reported as gains on sale of loans	$ 200	$ 1,000	900	2,300
Changes in other intangible assets
Balance, beginning of period			11,865	14,718
Additions			911	2,269
Amortization	(700)	(1,300)	(2,800)	(4,558)
Balance, end of period	9,976	12,429	9,976	12,429
Fair market value and key assumptions used in determining the fair market value
Fair market value, beginning of period			12,003	15,820
Fair market value, end of period	10,352	12,694	10,352	12,694
Gross carrying value, accumulated amortization and net carrying value related to intangible assets
Gross Carrying Value	71,820		71,820		$ 70,909
Accumulated Amortization	(61,844)		(61,844)		(59,044)
Other intangible assets	9,976	12,429	9,976	12,429	11,865
Estimated Amortization Expense
2021 (remainder)	628		628
2021	2,216		2,216
2022	1,776		1,776
2023	1,444		1,444
2024	1,190		1,190
2025	993		993
Thereafter	1,729		1,729
Other intangible assets	$ 9,976	$ 12,429	$ 9,976	$ 12,429	$ 11,865
Measurement Input, Discount Rate | Mortgage Servicing Rights
Fair market value and key assumptions used in determining the fair market value
Weighted average prepayment speed assumption	0.096	0.096	0.096	0.096
Measurement Input, Constant Prepayment Rate | Mortgage Servicing Rights
Fair market value and key assumptions used in determining the fair market value
Weighted average prepayment speed assumption	0.180	0.243	0.180	0.243