Loans - Activity in the Allowance for Credit Losses on Loans by Portfolio Segment (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance			$ 281,495
Ending Balance	$ 290,258		290,258
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	91,420	$ 95,484	98,439	$ 87,569
Credit loss expense (benefit)	(763)	2,669	(3,952)	17,165
Charge-offs	(2,585)	(2,742)	(8,638)	(11,241)
Recoveries	1,247	1,256	3,470	3,174
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Write-offs, Net	(1,338)	(1,486)	(5,168)	(8,067)
Ending Balance	89,319	96,667	89,319	96,667
Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	9,407	10,389	11,563	9,992
Credit loss expense (benefit)	(1,603)	(2,343)	(4,100)	(2,428)
Charge-offs	0	0	(17)	(52)
Recoveries	242	353	600	887
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Write-offs, Net	242	353	583	835
Ending Balance	8,046	8,399	8,046	8,399
Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	142,505	140,923	135,110	143,205
Credit loss expense (benefit)	5,126	86	14,616	2,439
Charge-offs	0	0	(2,103)	(4,639)
Recoveries	1	6	9	10
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Write-offs, Net	1	6	(2,094)	(4,629)
Ending Balance	147,632	141,015	147,632	141,015
Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	29,146	21,707	25,637	19,106
Credit loss expense (benefit)	7,460	3,115	13,800	7,365
Charge-offs	(2,195)	(1,849)	(5,871)	(4,099)
Recoveries	328	386	1,173	987
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Write-offs, Net	(1,867)	(1,463)	(4,698)	(3,112)
Ending Balance	34,739	23,359	34,739	23,359
Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	11,234	9,300	10,746	10,279
Credit loss expense (benefit)	4,690	5,480	12,031	12,960
Charge-offs	(8,538)	(7,022)	(21,634)	(21,156)
Recoveries	3,136	3,023	9,379	8,698
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Write-offs, Net	(5,402)	(3,999)	(12,255)	(12,458)
Ending Balance	10,522	10,781	10,522	10,781
Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	283,712	277,803	281,495	270,151
Credit loss expense (benefit)	14,910	9,007	32,395	37,501
Charge-offs	(13,318)	(11,613)	(38,263)	(41,187)
Recoveries	4,954	5,024	14,631	13,756
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Write-offs, Net	(8,364)	(6,589)	(23,632)	(27,431)
Ending Balance	$ 290,258	$ 280,221	$ 290,258	$ 280,221