Loans Loans - Allowance for Credit Loss By Loan Class Calculated in Accordance With CECL Methodology (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Mar. 31, 2026	Dec. 31, 2025	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	$ 283,712		$ 281,495
Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	91,420	$ 98,888	98,439	$ 95,484	$ 94,307	$ 87,569
Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	9,407	11,082	11,563	10,389	10,256	9,992
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	142,505	138,042	135,110	140,923	143,177	143,205
Total consumer real estate loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	29,146	27,394	25,637	21,707	18,924	19,106
Consumer Loan [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	11,234	10,809	10,746	9,300	8,824	10,279
Loans Receivable [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	283,712	$ 286,215	281,495	$ 277,803	$ 275,488	$ 270,151
Modeled Expected Credit Losses [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	103,526		110,052
Modeled Expected Credit Losses [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	50,143		56,114
Modeled Expected Credit Losses [Member] | Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	5,888		7,215
Modeled Expected Credit Losses [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	16,331		17,018
Modeled Expected Credit Losses [Member] | Total consumer real estate loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	24,993		24,390
Modeled Expected Credit Losses [Member] | Consumer Loan [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	6,171		5,315
Q-factor adjustments [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	167,657		152,171
Q-factor adjustments [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	33,592		25,706
Q-factor adjustments [Member] | Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	2,819		3,648
Q-factor adjustments [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	123,539		116,857
Q-factor adjustments [Member] | Total consumer real estate loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	2,725		610
Q-factor adjustments [Member] | Consumer Loan [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	4,982		5,350
Specific Valuation Allowances [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	12,529		19,272
Specific Valuation Allowances [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	7,685		16,619
Specific Valuation Allowances [Member] | Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	700		700
Specific Valuation Allowances [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	2,635		1,235
Specific Valuation Allowances [Member] | Total consumer real estate loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	1,428		637
Specific Valuation Allowances [Member] | Consumer Loan [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	$ 81		$ 81