Loans and Allowances for Credit Losses, By Aging Category (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	$ 49,542	$ 48,371
Current and Past Due Performing Loans	24,553,581	23,904,968
30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	37,177	55,411
60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	26,220	50,082
90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	79,881	93,644
Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	24,410,303	23,705,831
Commercial [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	2,866	0
Current and Past Due Performing Loans	15,623,409	14,803,769
Commercial [Member] | 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	2,419	18,433
Commercial [Member] | 60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	5,736	31,447
Commercial [Member] | 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	19,566	29,890
Commercial [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	15,595,688	14,723,999
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	4,231,058	4,143,233
Commercial [Member] | Healthcare [Member] | 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	1,375	18,019
Commercial [Member] | Healthcare [Member] | 60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	4,415	30,290
Commercial [Member] | Healthcare [Member] | 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	10,763	23,588
Commercial [Member] | Healthcare [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	4,214,505	4,071,336
Commercial [Member] | Services [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	72	0
Current and Past Due Performing Loans	3,577,144	3,576,223
Commercial [Member] | Services [Member] | 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	0	2
Commercial [Member] | Services [Member] | 60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	1,158	0
Commercial [Member] | Services [Member] | 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	435	434
Commercial [Member] | Services [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	3,575,551	3,575,787
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	3,451,485	3,437,101
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	3,451,485	3,437,101
Commercial [Member] | General business [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	2,794	0
Current and Past Due Performing Loans	4,363,722	3,647,212
Commercial [Member] | General business [Member] | 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	1,044	412
Commercial [Member] | General business [Member] | 60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	163	1,157
Commercial [Member] | General business [Member] | 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	8,368	5,868
Commercial [Member] | General business [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	4,354,147	3,639,775
Commercial real estate [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	0	3
Current and Past Due Performing Loans	5,083,575	5,337,647
Commercial real estate [Member] | 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	0	2,992
Commercial real estate [Member] | 60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	3,021	0
Commercial real estate [Member] | 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	7,138	7,174
Commercial real estate [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	5,073,416	5,327,481
Loans to individuals [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	46,676	48,368
Current and Past Due Performing Loans	3,846,597	3,763,552
Loans to individuals [Member] | 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	34,758	33,986
Loans to individuals [Member] | 60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	17,463	18,635
Loans to individuals [Member] | 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	53,177	56,580
Loans to individuals [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	3,741,199	3,654,351
Loans to individuals [Member] | Residential mortgage [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	97	36
Current and Past Due Performing Loans	2,281,226	2,160,640
Loans to individuals [Member] | Residential mortgage [Member] | 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	9,907	6,340
Loans to individuals [Member] | Residential mortgage [Member] | 60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	1,615	1,494
Loans to individuals [Member] | Residential mortgage [Member] | 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	1,759	2,879
Loans to individuals [Member] | Residential mortgage [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	2,267,945	2,149,927
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	46,579	48,201
Current and Past Due Performing Loans	131,825	149,807
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	23,918	25,085
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	15,796	17,053
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	51,418	53,547
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	40,693	54,122
Loans to individuals [Member] | Personal [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	0	131
Current and Past Due Performing Loans	1,433,546	1,453,105
Loans to individuals [Member] | Personal [Member] | 30 to 59 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	933	2,561
Loans to individuals [Member] | Personal [Member] | 60 to 89 Days [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	52	88
Loans to individuals [Member] | Personal [Member] | 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	0	154
Loans to individuals [Member] | Personal [Member] | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	$ 1,432,561	$ 1,450,302