DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Schedule of Interest Rate Swap Agreements and Non-hedging Derivative Assets and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022
Offsetting Assets [Line Items]
Notional Amount	$ 4,787,190	$ 4,524,514
Estimated Fair Value Asset (Liability)	(30,289)	(43,167)
Fair value estimates, impact of settled to market contract	26,700	38,300
Non-hedging derivatives
Offsetting Assets [Line Items]
Notional Amount	11,104	4,114
Estimated Fair Value Asset (Liability)	34	17
Commitments to lend \| Non-hedging derivatives
Offsetting Assets [Line Items]
Notional Amount	$ 11,104	$ 4,114
Weighted Average Maturity (in years)	2 months 12 days	2 months 12 days
Estimated Fair Value Asset (Liability)	$ 34	$ 17
Cash Flow Hedging
Offsetting Assets [Line Items]
Notional Amount	800,000	800,000
Estimated Fair Value Asset (Liability)	1,658	1,937
Cash Flow Hedging \| Interest rate swap \| Hedging derivatives
Offsetting Assets [Line Items]
Notional Amount	600,000
Cash Flow Hedging \| Interest rate swap \| Commercial Loan
Offsetting Assets [Line Items]
Notional Amount	$ 600,000	$ 400,000
Weighted Average Maturity (in years)	1 year 10 months 24 days	2 years 8 months 12 days
Weighted Average Rate - Received	3.64%	4.09%
Weighted Average Rate - Contract pay rate	5.35%	3.51%
Estimated Fair Value Asset (Liability)	$ 0	$ 0
Cash Flow Hedging \| Forward-starting interest rate swaps \| Commercial Loan
Offsetting Assets [Line Items]
Notional Amount		$ 200,000
Weighted Average Maturity (in years)		3 years 3 months 18 days
Weighted Average Rate - Received		0.00%
Weighted Average Rate - Contract pay rate		3.90%
Estimated Fair Value Asset (Liability)		$ 0
Cash Flow Hedging \| Interest rate collars \| Hedging derivatives
Offsetting Assets [Line Items]
Notional Amount	200,000
Cash Flow Hedging \| Interest rate collars \| Commercial Loan
Offsetting Assets [Line Items]
Notional Amount	$ 200,000	$ 200,000
Weighted Average Maturity (in years)	2 years 6 months	3 years 6 months
Estimated Fair Value Asset (Liability)	$ 1,658	$ 1,937
Economic Hedging \| Hedging derivatives
Offsetting Assets [Line Items]
Notional Amount	3,976,086	3,720,400
Estimated Fair Value Asset (Liability)	(31,981)	(45,121)
Economic Hedging \| Interest rate swap \| Tax advantaged economic development bonds
Offsetting Assets [Line Items]
Notional Amount	6,200
Economic Hedging \| Interest rate swap \| Hedging derivatives
Offsetting Assets [Line Items]
Notional Amount	3,600,000
Economic Hedging \| Interest rate swap \| Hedging derivatives \| Tax advantaged economic development bonds
Offsetting Assets [Line Items]
Notional Amount	$ 6,202	$ 7,062
Weighted Average Maturity (in years)	5 years 10 months 24 days	6 years 10 months 24 days
Weighted Average Rate - Received	5.82%	4.49%
Weighted Average Rate - Contract pay rate	5.09%	5.09%
Estimated Fair Value Asset (Liability)	$ (172)	$ (193)
Economic Hedging \| Interest rate swap \| Hedging derivatives \| Commercial loan
Offsetting Assets [Line Items]
Notional Amount	$ 1,795,562	$ 1,685,263
Weighted Average Maturity (in years)	4 years 10 months 24 days	5 years 8 months 12 days
Weighted Average Rate - Received	4.36%	4.11%
Weighted Average Rate - Contract pay rate	6.27%	5.55%
Estimated Fair Value Asset (Liability)	$ (63,865)	$ (95,114)
Economic Hedging \| Reverse interest rate swaps \| Hedging derivatives \| Commercial loan
Offsetting Assets [Line Items]
Notional Amount	$ 1,795,562	$ 1,685,263
Weighted Average Maturity (in years)	4 years 10 months 24 days	5 years 8 months 12 days
Weighted Average Rate - Received	6.27%	5.55%
Weighted Average Rate - Contract pay rate	4.36%	4.11%
Estimated Fair Value Asset (Liability)	$ 32,053	$ 50,267
Economic Hedging \| Risk participation agreements \| Hedging derivatives
Offsetting Assets [Line Items]
Notional Amount	$ 376,553	$ 341,885
Weighted Average Maturity (in years)	5 years 6 months	6 years 7 months 6 days
Estimated Fair Value Asset (Liability)	$ (18)	$ (89)
Economic Hedging \| Forward sale commitments \| Hedging derivatives
Offsetting Assets [Line Items]
Notional Amount	$ 2,207	$ 927
Weighted Average Maturity (in years)	2 months 12 days	2 months 12 days
Estimated Fair Value Asset (Liability)	$ 21	$ 8

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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