Loans and Allowances for Credit Losses, By Aging Category (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	$ 62,926	$ 52,504
Current and Past Due Performing Loans	24,865,194	24,114,724
30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	65,698	59,350
60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	16,934	21,775
90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	95,403	80,180
Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	24,687,159	23,953,419
Commercial [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	187	0
Current and Past Due Performing Loans	14,512,940	15,030,136
Commercial [Member] \| 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	18,389	28,845
Commercial [Member] \| 60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	83	837
Commercial [Member] \| 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	8,975	9,642
Commercial [Member] \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	14,485,493	14,990,812
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	3,878,543	3,967,533
Commercial [Member] \| Healthcare [Member] \| 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	15,107	25,778
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	8,788	9,613
Commercial [Member] \| Healthcare [Member] \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	3,854,648	3,932,142
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	3,710,643	3,643,203
Commercial [Member] \| Services [Member] \| 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	201	0
Commercial [Member] \| Services [Member] \| 60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	29	767
Commercial [Member] \| Services [Member] \| 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	0	0
Commercial [Member] \| Services [Member] \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	3,710,413	3,642,436
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	2,681,512	3,254,724
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	2,681,512	3,254,724
Commercial [Member] \| General business [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	187	0
Current and Past Due Performing Loans	4,242,242	4,164,676
Commercial [Member] \| General business [Member] \| 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	3,081	3,067
Commercial [Member] \| General business [Member] \| 60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	54	70
Commercial [Member] \| General business [Member] \| 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	187	29
Commercial [Member] \| General business [Member] \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	4,238,920	4,161,510
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	5,752,607	5,058,452
Commercial real estate [Member] \| 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	0	0
Commercial real estate [Member] \| 60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	233	0
Commercial real estate [Member] \| 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	6,765	9,785
Commercial real estate [Member] \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	5,745,609	5,048,667
Loans to individuals [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	62,739	52,504
Current and Past Due Performing Loans	4,599,647	4,026,136
Loans to individuals [Member] \| 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	47,309	30,505
Loans to individuals [Member] \| 60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	16,618	20,938
Loans to individuals [Member] \| 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	79,663	60,753
Loans to individuals [Member] \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	4,456,057	3,913,940
Loans to individuals [Member] \| Residential mortgage [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	148	0
Current and Past Due Performing Loans	2,676,366	2,436,958
Loans to individuals [Member] \| Residential mortgage [Member] \| 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	14,281	10,930
Loans to individuals [Member] \| Residential mortgage [Member] \| 60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	2,864	5,622
Loans to individuals [Member] \| Residential mortgage [Member] \| 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	7,680	3,773
Loans to individuals [Member] \| Residential mortgage [Member] \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	2,651,541	2,416,633
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	61,791	52,504
Current and Past Due Performing Loans	151,642	136,649
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	17,701	18,514
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	13,677	15,268
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	66,552	56,957
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	53,712	45,910
Loans to individuals [Member] \| Personal [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	800	0
Current and Past Due Performing Loans	1,771,639	1,452,529
Loans to individuals [Member] \| Personal [Member] \| 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	15,327	1,061
Loans to individuals [Member] \| Personal [Member] \| 60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	77	48
Loans to individuals [Member] \| Personal [Member] \| 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	5,431	23
Loans to individuals [Member] \| Personal [Member] \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	$ 1,750,804	$ 1,451,397