Loans and Allowances for Credit Losses, By Aging Category (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	$ 84,369	$ 76,535
Current and Past Due Performing Loans	26,187,393	25,651,462
30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	46,158	40,003
60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	2,578	22,748
90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	121,594	121,943
Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	26,017,063	25,466,768
Commercial [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	2,097	0
Current and Past Due Performing Loans	15,573,083	15,281,067
Commercial [Member] \| 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	1,550	9,178
Commercial [Member] \| 60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	275	8,638
Commercial [Member] \| 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	24,826	23,517
Commercial [Member] \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	15,546,432	15,239,734
Commercial [Member] \| Healthcare [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	0	0
Current and Past Due Performing Loans	3,955,763	4,008,208
Commercial [Member] \| Healthcare [Member] \| 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	0	0
Commercial [Member] \| Healthcare [Member] \| 60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	0	0
Commercial [Member] \| Healthcare [Member] \| 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	19,950	23,488
Commercial [Member] \| Healthcare [Member] \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	3,935,813	3,984,720
Commercial [Member] \| Services [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	0	0
Current and Past Due Performing Loans	3,901,933	3,911,917
Commercial [Member] \| Services [Member] \| 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	100	3,476
Commercial [Member] \| Services [Member] \| 60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	28	4,796
Commercial [Member] \| Services [Member] \| 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	29	29
Commercial [Member] \| Services [Member] \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	3,901,776	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	3,005,693	2,882,242
Commercial [Member] \| Energy [Member] \| 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	0	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	3,005,693	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	228,242	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	228,242	177,765
Commercial [Member] \| General business [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	2,097	0
Current and Past Due Performing Loans	4,481,452	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	1,450	5,702
Commercial [Member] \| General business [Member] \| 60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	247	3,842
Commercial [Member] \| General business [Member] \| 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	4,847	0
Commercial [Member] \| General business [Member] \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	4,474,908	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	5,884,679	5,672,006
Commercial real estate [Member] \| 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	0	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	6,601	6,697
Commercial real estate [Member] \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	5,878,078	5,664,492
Loans to individuals [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	82,272	76,535
Current and Past Due Performing Loans	4,729,631	4,698,389
Loans to individuals [Member] \| 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	44,608	30,008
Loans to individuals [Member] \| 60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	2,303	14,110
Loans to individuals [Member] \| 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	90,167	91,729
Loans to individuals [Member] \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	4,592,553	4,562,542
Loans to individuals [Member] \| Residential mortgage [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	314	0
Current and Past Due Performing Loans	2,784,134	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	16,182	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	843	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	5,211	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	2,761,898	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	81,958	76,535
Current and Past Due Performing Loans	160,254	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	27,087	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	0	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	84,830	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	48,337	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	1,785,243	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	1,339	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	1,460	551
Loans to individuals [Member] \| Personal [Member] \| 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	126	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	$ 1,782,318	$ 1,799,975