LOANS (Loans held to maturity) (Details) - USD ($)	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022
Loans and Leases Receivable Disclosure [Line Items]
Total loans receivable held to maturity	$ 11,608,309,000		$ 12,068,645,000
Allowance for credit losses	(126,861,000)	$ (123,934,000)	(122,566,000)	$ (111,198,000)	$ (112,707,000)	$ (109,483,000)
Loans receivable, net	11,481,448,000		11,946,079,000
Paycheck Protection Program ("PPP")
Loans and Leases Receivable Disclosure [Line Items]
Allowance for credit losses	0
Commercial and industrial | Commercial and industrial
Loans and Leases Receivable Disclosure [Line Items]
Total loans receivable held to maturity	3,541,239,000		3,652,047,000
Allowance for credit losses	(44,800,000)	(41,105,000)	(40,679,000)	(29,396,000)	(31,823,000)	(29,071,000)
Commercial and industrial | Paycheck Protection Program ("PPP")
Loans and Leases Receivable Disclosure [Line Items]
Total loans receivable held to maturity	1,864,000		2,777,000
Allowance for credit losses	0		0
Commercial and industrial | Owner occupied commercial real estate
Loans and Leases Receivable Disclosure [Line Items]
Total loans receivable held to maturity	2,555,964,000		2,638,175,000
Allowance for credit losses	(14,714,000)	(14,395,000)	(17,156,000)	(14,709,000)	(14,151,000)	(13,948,000)
Commercial and industrial | Non-owner occupied commercial real estate
Loans and Leases Receivable Disclosure [Line Items]
Total loans receivable held to maturity	2,434,258,000		2,553,711,000
Allowance for credit losses	(13,697,000)	(15,770,000)	(17,249,000)	(17,976,000)	(17,062,000)	(16,539,000)
Commercial and industrial | Real Estate Construction
Loans and Leases Receivable Disclosure [Line Items]
Total loans receivable held to maturity	1,082,726,000		1,011,716,000
Allowance for credit losses	(32,210,000)	(34,925,000)	(28,773,000)	(28,246,000)	(30,138,000)	(29,998,000)
Agricultural and agricultural real estate
Loans and Leases Receivable Disclosure [Line Items]
Total loans receivable held to maturity	802,958,000		919,184,000
Allowance for credit losses	(8,905,000)	(5,108,000)	(4,292,000)	(3,511,000)	(2,546,000)	(2,634,000)
Residential real estate
Loans and Leases Receivable Disclosure [Line Items]
Total loans receivable held to maturity	733,401,000		797,829,000
Allowance for credit losses	(5,036,000)	(5,155,000)	(5,845,000)	(7,644,000)	(7,564,000)	(7,711,000)
Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total loans receivable held to maturity	455,899,000		493,206,000
Allowance for credit losses	$ (7,499,000)	$ (7,476,000)	$ (8,572,000)	$ (9,716,000)	$ (9,423,000)	$ (9,582,000)