v3.26.1
FAIR VALUE - Schedule of Carrying Amounts and Estimated Fair Values of Financial Instruments, Not Carried at Fair Value (Details) - USD ($)
$ in Thousands
Jun. 30, 2026
Dec. 31, 2025
Jun. 30, 2025
Financial Assets      
Cash, due from banks, money market,    and other interest-earning investments $ 1,768,180 $ 1,826,177  
Loans, net:      
Loans, net 50,192,073 48,194,642  
Deposits:      
Noninterest-bearing demand deposits 12,665,278 13,247,483  
Time deposits 10,491,126 9,661,024  
Federal funds purchased and interbank borrowings 250,389 100,197  
Securities sold under agreements to repurchase 265,301 261,366 $ 297,637
FHLB advances 6,520,296 6,237,375  
Other borrowings 1,387,997 852,429  
Carrying Value      
Financial Assets      
Cash, due from banks, money market,    and other interest-earning investments 1,768,180 1,826,177  
Loans, net:      
Accrued interest receivable 301,860 306,812  
Deposits:      
Noninterest-bearing demand deposits 12,665,278 13,247,483  
Checking, NOW, savings, and money market    interest-bearing deposits 32,990,366 32,179,688  
Time deposits 10,491,126 9,661,024  
Federal funds purchased and interbank borrowings 250,389 100,197  
Securities sold under agreements to repurchase 265,301 261,366  
FHLB advances 6,520,296 6,237,375  
Other borrowings 1,387,997 852,429  
Accrued interest payable 71,420 65,291  
Standby letters of credit 1,929 1,672  
Off-Balance Sheet Financial Instruments      
Commitments to extend credit 0 0  
Carrying Value | U.S. government-sponsored entities and agencies      
Investment securities held-to-maturity:      
Investment securities held to maturity 825,359 840,435  
Carrying Value | Mortgage-backed securities - Agency      
Investment securities held-to-maturity:      
Investment securities held to maturity 881,022 910,323  
Carrying Value | States and political subdivisions      
Investment securities held-to-maturity:      
Investment securities held to maturity 1,138,123 1,144,730  
Carrying Value | Commercial      
Loans, net:      
Loans, net 15,856,832 14,737,809  
Carrying Value | Commercial real estate      
Loans, net:      
Loans, net 22,270,561 21,780,686  
Carrying Value | Residential real estate      
Loans, net:      
Loans, net 8,720,382 8,433,102  
Carrying Value | Consumer credit      
Loans, net:      
Loans, net 3,344,298 3,243,045  
Estimate of Fair Value Measurement | Quoted Prices in Active Markets for Identical Assets (Level 1)      
Financial Assets      
Cash, due from banks, money market,    and other interest-earning investments 1,768,180 1,826,177  
Loans, net:      
Accrued interest receivable 867 894  
Deposits:      
Noninterest-bearing demand deposits 12,665,278 13,247,483  
Checking, NOW, savings, and money market    interest-bearing deposits 32,990,366 32,179,688  
Time deposits 0 0  
Federal funds purchased and interbank borrowings 250,389 100,197  
Securities sold under agreements to repurchase 265,301 261,366  
FHLB advances 0 0  
Other borrowings 0 0  
Accrued interest payable 0 0  
Standby letters of credit 0 0  
Off-Balance Sheet Financial Instruments      
Commitments to extend credit 0 0  
Estimate of Fair Value Measurement | Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. government-sponsored entities and agencies      
Investment securities held-to-maturity:      
Investment securities held to maturity 0 0  
Estimate of Fair Value Measurement | Quoted Prices in Active Markets for Identical Assets (Level 1) | Mortgage-backed securities - Agency      
Investment securities held-to-maturity:      
Investment securities held to maturity 0 0  
Estimate of Fair Value Measurement | Quoted Prices in Active Markets for Identical Assets (Level 1) | States and political subdivisions      
Investment securities held-to-maturity:      
Investment securities held to maturity 0 0  
Estimate of Fair Value Measurement | Quoted Prices in Active Markets for Identical Assets (Level 1) | Commercial      
Loans, net:      
Loans, net 0 0  
Estimate of Fair Value Measurement | Quoted Prices in Active Markets for Identical Assets (Level 1) | Commercial real estate      
Loans, net:      
Loans, net 0 0  
Estimate of Fair Value Measurement | Quoted Prices in Active Markets for Identical Assets (Level 1) | Residential real estate      
Loans, net:      
Loans, net 0 0  
Estimate of Fair Value Measurement | Quoted Prices in Active Markets for Identical Assets (Level 1) | Consumer credit      
Loans, net:      
Loans, net 0 0  
Estimate of Fair Value Measurement | Significant Other Observable Inputs (Level 2)      
Financial Assets      
Cash, due from banks, money market,    and other interest-earning investments 0 0  
Loans, net:      
Accrued interest receivable 77,261 77,288  
Deposits:      
Noninterest-bearing demand deposits 0 0  
Checking, NOW, savings, and money market    interest-bearing deposits 0 0  
Time deposits 10,442,674 9,540,748  
Federal funds purchased and interbank borrowings 0 0  
Securities sold under agreements to repurchase 0 0  
FHLB advances 6,501,492 6,229,752  
Other borrowings 1,404,069 853,938  
Accrued interest payable 71,420 65,291  
Standby letters of credit 0 0  
Off-Balance Sheet Financial Instruments      
Commitments to extend credit 0 0  
Estimate of Fair Value Measurement | Significant Other Observable Inputs (Level 2) | U.S. government-sponsored entities and agencies      
Investment securities held-to-maturity:      
Investment securities held to maturity 687,544 710,909  
Estimate of Fair Value Measurement | Significant Other Observable Inputs (Level 2) | Mortgage-backed securities - Agency      
Investment securities held-to-maturity:      
Investment securities held to maturity 745,684 782,818  
Estimate of Fair Value Measurement | Significant Other Observable Inputs (Level 2) | States and political subdivisions      
Investment securities held-to-maturity:      
Investment securities held to maturity 1,034,980 1,046,511  
Estimate of Fair Value Measurement | Significant Other Observable Inputs (Level 2) | Commercial      
Loans, net:      
Loans, net 0 0  
Estimate of Fair Value Measurement | Significant Other Observable Inputs (Level 2) | Commercial real estate      
Loans, net:      
Loans, net 0 0  
Estimate of Fair Value Measurement | Significant Other Observable Inputs (Level 2) | Residential real estate      
Loans, net:      
Loans, net 0 0  
Estimate of Fair Value Measurement | Significant Other Observable Inputs (Level 2) | Consumer credit      
Loans, net:      
Loans, net 0 0  
Estimate of Fair Value Measurement | Significant Unobservable Inputs (Level 3)      
Financial Assets      
Cash, due from banks, money market,    and other interest-earning investments 0 0  
Loans, net:      
Accrued interest receivable 223,732 228,630  
Deposits:      
Noninterest-bearing demand deposits 0 0  
Checking, NOW, savings, and money market    interest-bearing deposits 0 0  
Time deposits 0 0  
Federal funds purchased and interbank borrowings 0 0  
Securities sold under agreements to repurchase 0 0  
FHLB advances 0 0  
Other borrowings 0 0  
Accrued interest payable 0 0  
Standby letters of credit 1,929 1,672  
Off-Balance Sheet Financial Instruments      
Commitments to extend credit 5,379 5,687  
Estimate of Fair Value Measurement | Significant Unobservable Inputs (Level 3) | U.S. government-sponsored entities and agencies      
Investment securities held-to-maturity:      
Investment securities held to maturity 0 0  
Estimate of Fair Value Measurement | Significant Unobservable Inputs (Level 3) | Mortgage-backed securities - Agency      
Investment securities held-to-maturity:      
Investment securities held to maturity 0 0  
Estimate of Fair Value Measurement | Significant Unobservable Inputs (Level 3) | States and political subdivisions      
Investment securities held-to-maturity:      
Investment securities held to maturity 0 0  
Estimate of Fair Value Measurement | Significant Unobservable Inputs (Level 3) | Commercial      
Loans, net:      
Loans, net 15,972,494 14,831,563  
Estimate of Fair Value Measurement | Significant Unobservable Inputs (Level 3) | Commercial real estate      
Loans, net:      
Loans, net 22,528,236 21,806,075  
Estimate of Fair Value Measurement | Significant Unobservable Inputs (Level 3) | Residential real estate      
Loans, net:      
Loans, net 7,975,684 7,526,511  
Estimate of Fair Value Measurement | Significant Unobservable Inputs (Level 3) | Consumer credit      
Loans, net:      
Loans, net $ 3,189,201 $ 3,027,561