v3.26.1
Fair Value - Estimated fair value and related carrying amount, of the Company's financial instruments (Details) - USD ($)
$ in Thousands
 6 Months Ended 12 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Dec. 31, 2025
Financial assets:      
Trading securities $ 191,094   $ 110,183
Financial liabilities:      
Other derivative financial instruments (mortgage banking related) 51,918 $ (275,258)  
Carrying Amount      
Financial assets:      
Cash and cash equivalents 2,350,312   3,172,483
Trading securities 191,094   110,183
Investment securities 8,920,917   8,715,214
Loans held for sale 405,441   345,343
Loans, net of allowance for credit losses 50,260,208   48,013,330
Accrued interest receivable 238,893   233,265
Mortgage servicing rights 91,442   84,032
SBA servicing asset 4,954   5,512
Interest rate swap - non-designated hedge 147,342   221,835
Other derivative financial instruments (mortgage banking related) $ 1,547   $ 1,051
Derivative Asset, Statement of Financial Position [Extensible Enumeration] Derivative Asset, Noncurrent   Derivative Asset, Noncurrent
Financial liabilities:      
Noninterest-bearing $ 13,451,094   $ 13,375,697
Interest-bearing other than time deposits 35,038,294   34,410,867
Time deposits 7,860,422   7,359,233
Federal funds purchased and securities sold under agreements to repurchase 569,486   618,215
Corporate and subordinated debentures 696,749   696,536
Other borrowings 300,000    
Accrued interest payable 34,948   48,972
Interest rate swap - non-designated hedge 606,404   554,433
Other derivative financial instruments (mortgage banking related) 261   315
Fair Value      
Financial assets:      
Cash and cash equivalents 2,350,312   3,172,483
Trading securities 191,094   110,183
Investment securities 8,606,205   8,400,034
Loans held for sale 406,234   348,381
Loans, net of allowance for credit losses 49,968,238   47,378,022
Accrued interest receivable 238,893   233,265
Mortgage servicing rights 91,442   84,032
SBA servicing asset 4,954   5,512
Interest rate swap - non-designated hedge 147,342   221,835
Other derivative financial instruments (mortgage banking related) 1,547   1,051
Financial liabilities:      
Noninterest-bearing 13,451,094   13,375,697
Interest-bearing other than time deposits 35,038,294   34,410,867
Time deposits 7,840,476   7,347,648
Federal funds purchased and securities sold under agreements to repurchase 569,486   618,215
Corporate and subordinated debentures 669,627   683,772
Other borrowings 299,995    
Accrued interest payable 34,948   48,972
Interest rate swap - non-designated hedge 606,404   554,433
Other derivative financial instruments (mortgage banking related) 261   315
Quoted Prices In Active Markets for Identical Assets (Level 1)      
Financial assets:      
Cash and cash equivalents 2,350,312   3,172,483
Investment securities 287,033   274,730
Significant Other Observable Inputs (Level 2)      
Financial assets:      
Trading securities 191,094   110,183
Investment securities 8,239,219   8,046,606
Loans held for sale 406,234   348,381
Accrued interest receivable 36,943   35,302
Interest rate swap - non-designated hedge 147,342   221,835
Other derivative financial instruments (mortgage banking related) 1,547   1,051
Financial liabilities:      
Noninterest-bearing 13,451,094   13,375,697
Interest-bearing other than time deposits 35,038,294   34,410,867
Time deposits 7,840,476   7,347,648
Federal funds purchased and securities sold under agreements to repurchase 569,486   618,215
Corporate and subordinated debentures 669,627   683,772
Other borrowings 299,995    
Accrued interest payable 34,948   48,972
Interest rate swap - non-designated hedge 606,404   554,433
Other derivative financial instruments (mortgage banking related) 261   315
Significant Unobservable Inputs (Level 3)      
Financial assets:      
Investment securities 79,953   78,698
Loans, net of allowance for credit losses 49,968,238   47,378,022
Accrued interest receivable 201,950   197,963
Mortgage servicing rights 91,442   84,032
SBA servicing asset $ 4,954   $ 5,512