GOODWILL AND IDENTIFIABLE INTANGIBLE ASSETS (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Identifiable Intangible Assets
Gross Carrying Amount	$ 197,186,000	$ 186,202,000
Accumulated Amortization	(136,190,000)	(120,976,000)
Net Carrying Amount	60,996,000	65,226,000
Estimated aggregate amortization expense for each of five succeeding fiscal years
2023	13,698,000
2024	11,601,000
2025	9,883,000
2026	8,745,000
2027	3,333,000
Thereafter	13,736,000
Net Carrying Amount	60,996,000	65,226,000
Components of goodwill
Goodwill, beginning of period	799,109,000	793,708,000
Goodwill, activity	42,732,000	5,401,000
Goodwill, end of period	841,841,000	799,109,000
Changes in carrying value of MSRs and the associated valuation allowance
Carrying value before valuation allowance at beginning of period	1,144,000	1,430,000
Additions	83,000	233,000
Acquisitions	2,879,000	0
Amortization	(801,000)	(519,000)
Carrying value before valuation allowance at end of period	3,305,000	1,144,000
Valuation allowance balance at beginning of period	0	(219,000)
Impairment charges	(676,000)	(55,000)
Impairment recoveries	0	274,000
Valuation allowance balance at end of period	(676,000)	0
Net carrying value at end of period	2,629,000	1,144,000
Fair value of MSRs at end of period	5,107,000	1,469,000
Principal balance of mortgage loans sold during the year	5,309,000	20,133,000
Principal balance of loans serviced for others	583,109,000	296,506,000
Custodial escrow balances maintained in connection with loans serviced for others	10,534,000	4,934,000
Impairment loss for goodwill	$ 0	$ 0
Key economic assumptions used to estimate the value of the MSRs
Weighted-average contractual life (in years)	21 years 7 months 6 days	21 years 4 months 24 days
Weighted-average constant prepayment rate (CPR)	7.70%	24.50%
Weighted-average discount rate	4.90%	2.60%
Core deposit intangibles
Identifiable Intangible Assets
Gross Carrying Amount	$ 77,373,000	$ 69,403,000
Accumulated Amortization	(65,069,000)	(60,316,000)
Net Carrying Amount	12,304,000	9,087,000
Estimated aggregate amortization expense for each of five succeeding fiscal years
Net Carrying Amount	12,304,000	9,087,000
Other intangibles
Identifiable Intangible Assets
Gross Carrying Amount	119,813,000	116,799,000
Accumulated Amortization	(71,121,000)	(60,660,000)
Net Carrying Amount	48,692,000	56,139,000
Estimated aggregate amortization expense for each of five succeeding fiscal years
Net Carrying Amount	$ 48,692,000	$ 56,139,000