LOANS (Loans held to maturity) (Details) - USD ($)	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Loans and Leases Receivable Disclosure [Line Items]
Total loans receivable held to maturity	$ 11,644,641,000	$ 12,068,645,000
Allowance for credit losses	(123,934,000)	(122,566,000)	$ (112,707,000)	$ (109,483,000)
Loans receivable, net	11,520,707,000	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	3,545,051,000	3,652,047,000
Allowance for credit losses	(41,105,000)	(40,679,000)	(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	2,172,000	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	2,545,033,000	2,638,175,000
Allowance for credit losses	(14,395,000)	(17,156,000)	(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	2,495,068,000	2,553,711,000
Allowance for credit losses	(15,770,000)	(17,249,000)	(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	1,041,583,000	1,011,716,000
Allowance for credit losses	(34,925,000)	(28,773,000)	(30,138,000)	(29,998,000)
Agricultural and agricultural real estate
Loans and Leases Receivable Disclosure [Line Items]
Total loans receivable held to maturity	809,876,000	919,184,000
Allowance for credit losses	(5,108,000)	(4,292,000)	(2,546,000)	(2,634,000)
Residential real estate
Loans and Leases Receivable Disclosure [Line Items]
Total loans receivable held to maturity	756,021,000	797,829,000
Allowance for credit losses	(5,155,000)	(5,845,000)	(7,564,000)	(7,711,000)
Consumer
Loans and Leases Receivable Disclosure [Line Items]
Total loans receivable held to maturity	449,837,000	493,206,000
Allowance for credit losses	$ (7,476,000)	$ (8,572,000)	$ (9,423,000)	$ (9,582,000)