Loans - Age Analysis of Past Due Loans, Segregated by Class of Loans (Detail) - USD ($) $ in Thousands	Jun. 30, 2026	Dec. 31, 2025
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	$ 22,975,658	$ 21,891,812
Financing Receivable, Excluding Accrued Interest, 90 Days or More Past Due, Still Accruing	13,933
Loans Held For Sale
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	9,421
Financing Receivable, Excluding Accrued Interest, 90 Days or More Past Due, Still Accruing	0
Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	6,325,658	6,306,980
Financing Receivable, Excluding Accrued Interest, 90 Days or More Past Due, Still Accruing	4,462
Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	1,133,640	1,094,669
Financing Receivable, Excluding Accrued Interest, 90 Days or More Past Due, Still Accruing	0
Commercial Real Estate Owner Occupied
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	4,297,680	3,987,913
Financing Receivable, Excluding Accrued Interest, 90 Days or More Past Due, Still Accruing	1,034
Commercial Real Estate Owner Occupied | Loans Held For Sale
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	9,282
Financing Receivable, Excluding Accrued Interest, 90 Days or More Past Due, Still Accruing	0
Commercial Real Estate Non-Owner Occupied
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	3,970,141	3,773,028
Financing Receivable, Excluding Accrued Interest, 90 Days or More Past Due, Still Accruing	0
Construction Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	2,720,755	2,549,869
Financing Receivable, Excluding Accrued Interest, 90 Days or More Past Due, Still Accruing	1,142
Construction Loans [Member] | Loans Held For Sale
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	139
Financing Receivable, Excluding Accrued Interest, 90 Days or More Past Due, Still Accruing	0
Total consumer real estate loans [Member]
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	4,069,982	3,718,668
Financing Receivable, Excluding Accrued Interest, 90 Days or More Past Due, Still Accruing	6,932
Consumer Loan [Member]
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	457,802	$ 460,685
Financing Receivable, Excluding Accrued Interest, 90 Days or More Past Due, Still Accruing	363
Financing Receivables, 30 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	155,286
Financing Receivables, 30 to 89 Days Past Due [Member] | Loans Held For Sale
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	110
Financing Receivables, 30 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	20,844
Financing Receivables, 30 to 89 Days Past Due [Member] | Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	20,586
Financing Receivables, 30 to 89 Days Past Due [Member] | Commercial Real Estate Owner Occupied
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	17,965
Financing Receivables, 30 to 89 Days Past Due [Member] | Commercial Real Estate Owner Occupied | Loans Held For Sale
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	30
Financing Receivables, 30 to 89 Days Past Due [Member] | Commercial Real Estate Non-Owner Occupied
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	61,894
Financing Receivables, 30 to 89 Days Past Due [Member] | Construction Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	3,220
Financing Receivables, 30 to 89 Days Past Due [Member] | Construction Loans [Member] | Loans Held For Sale
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	80
Financing Receivables, 30 to 89 Days Past Due [Member] | Total consumer real estate loans [Member]
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	25,205
Financing Receivables, 30 to 89 Days Past Due [Member] | Consumer Loan [Member]
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	5,572
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	110,437
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Loans Held For Sale
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	581
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	19,160
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	2,523
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Real Estate Owner Occupied
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	10,897
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Real Estate Owner Occupied | Loans Held For Sale
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	522
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Real Estate Non-Owner Occupied
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	4,336
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Construction Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	57,196
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Construction Loans [Member] | Loans Held For Sale
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	59
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Total consumer real estate loans [Member]
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	15,705
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Consumer Loan [Member]
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	620
Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	265,723
Financial Asset, Past Due | Loans Held For Sale
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	691
Financial Asset, Past Due | Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	40,004
Financial Asset, Past Due | Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	23,109
Financial Asset, Past Due | Commercial Real Estate Owner Occupied
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	28,862
Financial Asset, Past Due | Commercial Real Estate Owner Occupied | Loans Held For Sale
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	552
Financial Asset, Past Due | Commercial Real Estate Non-Owner Occupied
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	66,230
Financial Asset, Past Due | Construction Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	60,416
Financial Asset, Past Due | Construction Loans [Member] | Loans Held For Sale
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	139
Financial Asset, Past Due | Total consumer real estate loans [Member]
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	40,910
Financial Asset, Past Due | Consumer Loan [Member]
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	6,192
Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	22,709,935
Financial Asset, Not Past Due | Loans Held For Sale
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	8,730
Financial Asset, Not Past Due | Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	6,285,654
Financial Asset, Not Past Due | Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	1,110,531
Financial Asset, Not Past Due | Commercial Real Estate Owner Occupied
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	4,268,818
Financial Asset, Not Past Due | Commercial Real Estate Owner Occupied | Loans Held For Sale
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	8,730
Financial Asset, Not Past Due | Commercial Real Estate Non-Owner Occupied
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	3,903,911
Financial Asset, Not Past Due | Construction Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	2,660,339
Financial Asset, Not Past Due | Construction Loans [Member] | Loans Held For Sale
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	0
Financial Asset, Not Past Due | Total consumer real estate loans [Member]
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	4,029,072
Financial Asset, Not Past Due | Consumer Loan [Member]
Financing Receivable, Past Due [Line Items]
Loans, net of unearned discounts	$ 451,610