Loans - Activity in the Allowance for Credit Losses on Loans by Portfolio Segment (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance			$ 281,495
Ending Balance	$ 283,712		283,712
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	98,888	$ 94,307	98,439	$ 87,569
Credit loss expense (benefit)	(5,668)	4,315	(3,189)	14,496
Charge-offs	(2,356)	(4,163)	(6,053)	(8,499)
Recoveries	556	1,025	2,223	1,918
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Write-offs, Net	(1,800)	(3,138)	(3,830)	(6,581)
Ending Balance	91,420	95,484	91,420	95,484
Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	11,082	10,256	11,563	9,992
Credit loss expense (benefit)	(1,748)	(47)	(2,497)	(85)
Charge-offs	(17)	0	(17)	(52)
Recoveries	90	180	358	534
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Write-offs, Net	73	180	341	482
Ending Balance	9,407	10,389	9,407	10,389
Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	138,042	143,177	135,110	143,205
Credit loss expense (benefit)	6,563	383	9,490	2,353
Charge-offs	(2,103)	(2,639)	(2,103)	(4,639)
Recoveries	3	2	8	4
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Write-offs, Net	(2,100)	(2,637)	(2,095)	(4,635)
Ending Balance	142,505	140,923	142,505	140,923
Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	27,394	18,924	25,637	19,106
Credit loss expense (benefit)	3,628	3,821	6,340	4,250
Charge-offs	(2,424)	(1,292)	(3,676)	(2,250)
Recoveries	548	254	845	601
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Write-offs, Net	(1,876)	(1,038)	(2,831)	(1,649)
Ending Balance	29,146	21,707	29,146	21,707
Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	10,809	8,824	10,746	10,279
Credit loss expense (benefit)	4,249	4,994	7,341	7,480
Charge-offs	(6,726)	(7,290)	(13,096)	(14,134)
Recoveries	2,902	2,772	6,243	5,675
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Write-offs, Net	(3,824)	(4,518)	(6,853)	(8,459)
Ending Balance	11,234	9,300	11,234	9,300
Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	286,215	275,488	281,495	270,151
Credit loss expense (benefit)	7,024	13,466	17,485	28,494
Charge-offs	(13,626)	(15,384)	(24,945)	(29,574)
Recoveries	4,099	4,233	9,677	8,732
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Write-offs, Net	(9,527)	(11,151)	(15,268)	(20,842)
Ending Balance	$ 283,712	$ 277,803	$ 283,712	$ 277,803