v3.26.3
Allowance for Credit Losses - Schedule of Allowance for Loan Losses and Carrying Amount of Loans (Detail) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2026
Sep. 30, 2026
Dec. 31, 2025
Financing Receivable, Allowance for Credit Losses [Line Items]      
Allowance for Loan and Lease Losses Beginning balance $ 299,504 $ 297,518 $ 271,844
Initial allowance for PCD loans (acquired during the period)     17,518
Charge-offs (12,283) (25,226) (50,912)
Recoveries 683 2,873 5,200
Provision 6,242 18,981 53,868
Allowance for Loan and Lease Losses Ending balance 294,146 294,146 297,518
Construction & Land Development [Member]      
Financing Receivable, Allowance for Credit Losses [Line Items]      
Allowance for Loan and Lease Losses Beginning balance 51,320 57,967 63,621
Initial allowance for PCD loans (acquired during the period)     4,584
Charge-offs 0 0 (408)
Recoveries 0 352 225
Provision 624 (6,375) (10,055)
Allowance for Loan and Lease Losses Ending balance 51,944 51,944 57,967
Bank Card [Member]      
Financing Receivable, Allowance for Credit Losses [Line Items]      
Allowance for Loan and Lease Losses Beginning balance 1,029 889 891
Initial allowance for PCD loans (acquired during the period)     0
Charge-offs (59) (174) (320)
Recoveries 7 27 55
Provision 33 268 263
Allowance for Loan and Lease Losses Ending balance 1,010 1,010 889
Commercial Real Estate [Member] | Owner-Occupied [Member]      
Financing Receivable, Allowance for Credit Losses [Line Items]      
Allowance for Loan and Lease Losses Beginning balance 13,753 13,564 11,852
Initial allowance for PCD loans (acquired during the period)     795
Charge-offs 0 0 (228)
Recoveries 16 251 318
Provision (2,757) (2,803) 827
Allowance for Loan and Lease Losses Ending balance 11,012 11,012 13,564
Commercial Real Estate [Member] | Nonowner-Occupied [Member]      
Financing Receivable, Allowance for Credit Losses [Line Items]      
Allowance for Loan and Lease Losses Beginning balance 107,602 96,716 74,522
Initial allowance for PCD loans (acquired during the period)     11,059
Charge-offs (10,642) (15,560) (35,798)
Recoveries 1 75 160
Provision 8,886 24,616 46,773
Allowance for Loan and Lease Losses Ending balance 105,847 105,847 96,716
Other Commercial [Member]      
Financing Receivable, Allowance for Credit Losses [Line Items]      
Allowance for Loan and Lease Losses Beginning balance 58,676 61,729 65,105
Initial allowance for PCD loans (acquired during the period)     872
Charge-offs (627) (6,203) (5,424)
Recoveries 294 993 2,309
Provision (837) 987 (1,133)
Allowance for Loan and Lease Losses Ending balance 57,506 57,506 61,729
Residential Real Estate [Member]      
Financing Receivable, Allowance for Credit Losses [Line Items]      
Allowance for Loan and Lease Losses Beginning balance 53,572 53,949 46,373
Initial allowance for PCD loans (acquired during the period)     208
Charge-offs (76) (351) (999)
Recoveries 14 100 704
Provision (257) (445) 7,663
Allowance for Loan and Lease Losses Ending balance 53,253 53,253 53,949
Other Consumer [Member]      
Financing Receivable, Allowance for Credit Losses [Line Items]      
Allowance for Loan and Lease Losses Beginning balance 13,552 12,704 9,480
Initial allowance for PCD loans (acquired during the period)     0
Charge-offs (879) (2,938) (7,735)
Recoveries 351 1,075 1,429
Provision 550 2,733 9,530
Allowance for Loan and Lease Losses Ending balance $ 13,574 $ 13,574 $ 12,704