Loans and Allowances for Credit Losses, By Aging Category (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	$ 48,371	$ 76,114
Current and Past Due Performing Loans	23,904,968	22,557,150
Current
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	23,705,831	22,355,864
30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	55,411	55,039
60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	50,082	51,614
90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	93,644	94,633
Commercial [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	0	396
Current and Past Due Performing Loans	14,803,769	14,212,499
Commercial [Member] | Current
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	14,723,999	14,169,066
Commercial [Member] | 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	18,433	7,255
Commercial [Member] | 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	31,447	30,365
Commercial [Member] | 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	29,890	5,813
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	4,143,233	3,845,017
Commercial [Member] | Healthcare [Member] | Current
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	4,071,336	3,812,164
Commercial [Member] | Healthcare [Member] | 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	18,019	5,914
Commercial [Member] | Healthcare [Member] | 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	30,290	26,480
Commercial [Member] | Healthcare [Member] | 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	23,588	459
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	3,576,223	3,431,521
Commercial [Member] | Services [Member] | Current
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	3,575,787	3,423,042
Commercial [Member] | Services [Member] | 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	2	1,060
Commercial [Member] | Services [Member] | 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	0	2,461
Commercial [Member] | Services [Member] | 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	434	4,958
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	3,437,101	3,424,790
Commercial [Member] | Energy [Member] | Current
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	3,437,101	3,424,766
Commercial [Member] | Energy [Member] | 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	0	24
Commercial [Member] | Energy [Member] | 60 to 89 Days Past Due [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] | General business [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	0	396
Current and Past Due Performing Loans	3,647,212	3,511,171
Commercial [Member] | General business [Member] | Current
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	3,639,775	3,509,094
Commercial [Member] | General business [Member] | 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	412	257
Commercial [Member] | General business [Member] | 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	1,157	1,424
Commercial [Member] | General business [Member] | 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	5,868	396
Commercial real estate [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	3	0
Current and Past Due Performing Loans	5,337,647	4,606,777
Commercial real estate [Member] | Current
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	5,327,481	4,606,029
Commercial real estate [Member] | 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	2,992	531
Commercial real estate [Member] | 60 to 89 Days Past Due [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	7,174	217
Loans to individuals [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	48,368	75,718
Current and Past Due Performing Loans	3,763,552	3,737,874
Loans to individuals [Member] | Current
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	3,654,351	3,580,769
Loans to individuals [Member] | 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	33,986	47,253
Loans to individuals [Member] | 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	18,635	21,249
Loans to individuals [Member] | 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	56,580	88,603
Loans to individuals [Member] | Residential mortgage [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	36	114
Current and Past Due Performing Loans	2,160,640	1,890,784
Loans to individuals [Member] | Residential mortgage [Member] | Current
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	2,149,927	1,872,155
Loans to individuals [Member] | Residential mortgage [Member] | 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	6,340	10,632
Loans to individuals [Member] | Residential mortgage [Member] | 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	1,494	1,828
Loans to individuals [Member] | Residential mortgage [Member] | 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	2,879	6,169
Loans to individuals [Member] | Residential mortgage [Member] | US Government Agency Insured Loans
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	48,201	75,604
Current and Past Due Performing Loans	149,807	245,940
Loans to individuals [Member] | Residential mortgage [Member] | US Government Agency Insured Loans | Current
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	54,122	108,019
Loans to individuals [Member] | Residential mortgage [Member] | US Government Agency Insured Loans | 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	25,085	36,119
Loans to individuals [Member] | Residential mortgage [Member] | US Government Agency Insured Loans | 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	17,053	19,400
Loans to individuals [Member] | Residential mortgage [Member] | US Government Agency Insured Loans | 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	53,547	82,402
Loans to individuals [Member] | Personal [Member]
Financing Receivable, Past Due [Line Items]
Past Due 90 Days or More and Accruing	131	0
Current and Past Due Performing Loans	1,453,105	1,601,150
Loans to individuals [Member] | Personal [Member] | Current
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	1,450,302	1,600,595
Loans to individuals [Member] | Personal [Member] | 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	2,561	502
Loans to individuals [Member] | Personal [Member] | 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	88	21
Loans to individuals [Member] | Personal [Member] | 90 Days or More [Member]
Financing Receivable, Past Due [Line Items]
Current and Past Due Performing Loans	$ 154	$ 32