Credit Quality - Schedule of Age Analysis of its Past Due Loans, Segregated by Class of Loans and Leases (Detail) - USD ($) $ in Thousands	Jun. 30, 2026	Dec. 31, 2025
Financing Receivable, Past Due [Line Items]
Loans, Past Due	$ 25,006,238	$ 24,720,620
Loans, Recorded Investment >90 Days & Accruing	11,346	4,974
30-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	69,338	55,065
90 Days or more Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	110,647	101,466
Total Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	179,985	156,531
Current & Other [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	24,826,253	24,564,089
Construction & Land Development [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	3,335,543	3,570,902
Loans, Recorded Investment >90 Days & Accruing	41	0
Construction & Land Development [Member] \| 30-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	4,483	1,508
Construction & Land Development [Member] \| 90 Days or more Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	2,728	1,301
Construction & Land Development [Member] \| Total Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	7,211	2,809
Construction & Land Development [Member] \| Current & Other [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	3,328,332	3,568,093
Commercial Real Estate [Member] \| Owner-Occupied [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	2,170,900	2,145,921
Loans, Recorded Investment >90 Days & Accruing	957	81
Commercial Real Estate [Member] \| Owner-Occupied [Member] \| 30-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	12,248	4,754
Commercial Real Estate [Member] \| Owner-Occupied [Member] \| 90 Days or more Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	2,173	1,830
Commercial Real Estate [Member] \| Owner-Occupied [Member] \| Total Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	14,421	6,584
Commercial Real Estate [Member] \| Owner-Occupied [Member] \| Current & Other [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	2,156,479	2,139,337
Commercial Real Estate [Member] \| Nonowner-Occupied [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	8,721,627	8,343,520
Loans, Recorded Investment >90 Days & Accruing	0	0
Commercial Real Estate [Member] \| Nonowner-Occupied [Member] \| 30-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	10,091	7,598
Commercial Real Estate [Member] \| Nonowner-Occupied [Member] \| 90 Days or more Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	71,212	71,038
Commercial Real Estate [Member] \| Nonowner-Occupied [Member] \| Total Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	81,303	78,636
Commercial Real Estate [Member] \| Nonowner-Occupied [Member] \| Current & Other [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	8,640,324	8,264,884
Other Commercial [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	3,806,987	3,784,833
Loans, Recorded Investment >90 Days & Accruing	246	591
Other Commercial [Member] \| 30-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	11,092	2,490
Other Commercial [Member] \| 90 Days or more Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	7,134	6,569
Other Commercial [Member] \| Total Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	18,226	9,059
Other Commercial [Member] \| Current & Other [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	3,788,761	3,775,774
Residential Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	6,180,010	6,098,262
Loans, Recorded Investment >90 Days & Accruing	9,845	3,701
Residential Real Estate [Member] \| 30-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	22,004	25,026
Residential Real Estate [Member] \| 90 Days or more Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	26,503	19,124
Residential Real Estate [Member] \| Total Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	48,507	44,150
Residential Real Estate [Member] \| Current & Other [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	6,131,503	6,054,112
Consumer [Member] \| Bankcard [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	9,363	9,686
Loans, Recorded Investment >90 Days & Accruing	44	54
Consumer [Member] \| Bankcard [Member] \| 30-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	27	28
Consumer [Member] \| Bankcard [Member] \| 90 Days or more Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	44	54
Consumer [Member] \| Bankcard [Member] \| Total Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	71	82
Consumer [Member] \| Bankcard [Member] \| Current & Other [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	9,292	9,604
Consumer [Member] \| Other Consumer [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	781,808	767,496
Loans, Recorded Investment >90 Days & Accruing	213	547
Consumer [Member] \| Other Consumer [Member] \| 30-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	9,393	13,661
Consumer [Member] \| Other Consumer [Member] \| 90 Days or more Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	853	1,550
Consumer [Member] \| Other Consumer [Member] \| Total Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	10,246	15,211
Consumer [Member] \| Other Consumer [Member] \| Current & Other [Member]
Financing Receivable, Past Due [Line Items]
Loans, Past Due	$ 771,562	$ 752,285