Loans and Allowances for Credit Losses, By Aging Category (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Dec. 31, 2025
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	$ 84,749	$ 76,535
Current and Past Due Performing Loans	27,083,715	25,651,462
30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	41,301	40,003
60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	23,412	22,748
90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	121,487	121,943
Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	26,897,515	25,466,768
Commercial [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	5,560	0
Current and Past Due Performing Loans	16,297,448	15,281,067
Commercial [Member] \| 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	6,217	9,178
Commercial [Member] \| 60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	3,788	8,638
Commercial [Member] \| 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	28,310	23,517
Commercial [Member] \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	16,259,133	15,239,734
Commercial [Member] \| Healthcare [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	4,307	0
Current and Past Due Performing Loans	4,083,814	4,008,208
Commercial [Member] \| Healthcare [Member] \| 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	32	0
Commercial [Member] \| Healthcare [Member] \| 60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	1	0
Commercial [Member] \| Healthcare [Member] \| 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	24,257	23,488
Commercial [Member] \| Healthcare [Member] \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	4,059,524	3,984,720
Commercial [Member] \| Services [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	3	0
Current and Past Due Performing Loans	4,099,879	3,911,917
Commercial [Member] \| Services [Member] \| 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	255	3,476
Commercial [Member] \| Services [Member] \| 60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	1,907	4,796
Commercial [Member] \| Services [Member] \| 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	31	29
Commercial [Member] \| Services [Member] \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	4,097,686	3,903,616
Commercial [Member] \| Energy [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	0	0
Current and Past Due Performing Loans	3,052,662	2,882,242
Commercial [Member] \| Energy [Member] \| 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	200	0
Commercial [Member] \| Energy [Member] \| 60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	0	0
Commercial [Member] \| Energy [Member] \| 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	0	0
Commercial [Member] \| Energy [Member] \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	3,052,462	2,882,242
Commercial [Member] \| Mortgage Finance
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	0	0
Current and Past Due Performing Loans	451,826	177,765
Commercial [Member] \| Mortgage Finance \| 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	0	0
Commercial [Member] \| Mortgage Finance \| 60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	0	0
Commercial [Member] \| Mortgage Finance \| 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	0	0
Commercial [Member] \| Mortgage Finance \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	451,826	177,765
Commercial [Member] \| General business [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	1,250	0
Current and Past Due Performing Loans	4,609,267	4,300,935
Commercial [Member] \| General business [Member] \| 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	5,730	5,702
Commercial [Member] \| General business [Member] \| 60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	1,880	3,842
Commercial [Member] \| General business [Member] \| 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	4,022	0
Commercial [Member] \| General business [Member] \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	4,597,635	4,291,391
Commercial real estate [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	0	0
Current and Past Due Performing Loans	5,885,330	5,672,006
Commercial real estate [Member] \| 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	252	817
Commercial real estate [Member] \| 60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	0	0
Commercial real estate [Member] \| 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	6,431	6,697
Commercial real estate [Member] \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	5,878,647	5,664,492
Loans to individuals [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	79,189	76,535
Current and Past Due Performing Loans	4,900,937	4,698,389
Loans to individuals [Member] \| 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	34,832	30,008
Loans to individuals [Member] \| 60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	19,624	14,110
Loans to individuals [Member] \| 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	86,746	91,729
Loans to individuals [Member] \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	4,759,735	4,562,542
Loans to individuals [Member] \| Residential mortgage [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	682	0
Current and Past Due Performing Loans	2,847,768	2,731,415
Loans to individuals [Member] \| Residential mortgage [Member] \| 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	18,847	8,570
Loans to individuals [Member] \| Residential mortgage [Member] \| 60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	8,123	2,182
Loans to individuals [Member] \| Residential mortgage [Member] \| 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	4,864	6,046
Loans to individuals [Member] \| Residential mortgage [Member] \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	2,815,934	2,714,617
Loans to individuals [Member] \| Residential mortgage [Member] \| US Government Agency Insured Loans [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	78,507	76,535
Current and Past Due Performing Loans	159,886	158,359
Loans to individuals [Member] \| Residential mortgage [Member] \| US Government Agency Insured Loans [Member] \| 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	15,530	17,975
Loans to individuals [Member] \| Residential mortgage [Member] \| US Government Agency Insured Loans [Member] \| 60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	11,480	11,377
Loans to individuals [Member] \| Residential mortgage [Member] \| US Government Agency Insured Loans [Member] \| 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	81,872	81,057
Loans to individuals [Member] \| Residential mortgage [Member] \| US Government Agency Insured Loans [Member] \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	51,004	47,950
Loans to individuals [Member] \| Personal [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	0	0
Current and Past Due Performing Loans	1,893,283	1,808,615
Loans to individuals [Member] \| Personal [Member] \| 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	455	3,463
Loans to individuals [Member] \| Personal [Member] \| 60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	21	551
Loans to individuals [Member] \| Personal [Member] \| 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	10	4,626
Loans to individuals [Member] \| Personal [Member] \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	$ 1,892,797	$ 1,799,975