Loans Past Due Status (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Summarized details of Loans
Current	$ 29,265,051	$ 28,983,708
Financing Receivable, Nonaccrual	178,346	148,997
Loans and Leases Receivable, Net of Deferred Income, Total	29,494,263	29,216,218
Nonaccrual Loans, Current Portion	$ 98,000	$ 80,000
Percent of current nonaccrual loans	55.00%	53.00%
Financing Receivable, Nonaccrual, Interest Income	$ 0	$ 0
Financing Receivable, Nonaccrual, No Allowance	20,000	23,000
30-59 Days Past Due
Summarized details of Loans
Total Past Due	25,617	38,113
60-89 Days Past Due
Summarized details of Loans
Total Past Due	22,831	23,712
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Summarized details of Loans
Total Past Due	2,417	21,689
Commercial and Industrial Sector
Summarized details of Loans
Current	9,785,140	9,663,587
Financing Receivable, Nonaccrual	72,243	62,022
Loans and Leases Receivable, Net of Deferred Income, Total	9,858,329	9,731,555
Commercial and Industrial Sector | 30-59 Days Past Due
Summarized details of Loans
Total Past Due	371	5,374
Commercial and Industrial Sector | 60-89 Days Past Due
Summarized details of Loans
Total Past Due	150	191
Commercial and Industrial Sector | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Summarized details of Loans
Total Past Due	426	380
Commercial real estate — owner occupied
Summarized details of Loans
Current	1,093,804	1,059,948
Financing Receivable, Nonaccrual	2,090	1,394
Loans and Leases Receivable, Net of Deferred Income, Total	1,095,894	1,061,700
Commercial real estate — owner occupied | 30-59 Days Past Due
Summarized details of Loans
Total Past Due	0	0
Commercial real estate — owner occupied | 60-89 Days Past Due
Summarized details of Loans
Total Past Due	0	358
Commercial real estate — owner occupied | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Summarized details of Loans
Total Past Due	0	0
Commercial and business lending
Summarized details of Loans
Current	10,878,944	10,723,536
Financing Receivable, Nonaccrual	74,333	63,416
Loans and Leases Receivable, Net of Deferred Income, Total	10,954,223	10,793,255
Commercial and business lending | 30-59 Days Past Due
Summarized details of Loans
Total Past Due	371	5,374
Commercial and business lending | 60-89 Days Past Due
Summarized details of Loans
Total Past Due	150	549
Commercial and business lending | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Summarized details of Loans
Total Past Due	426	380
Commercial real estate — investor
Summarized details of Loans
Current	4,997,335	5,086,117
Financing Receivable, Nonaccrual	18,697	0
Loans and Leases Receivable, Net of Deferred Income, Total	5,035,195	5,124,245
Commercial real estate — investor | 30-59 Days Past Due
Summarized details of Loans
Total Past Due	0	0
Commercial real estate — investor | 60-89 Days Past Due
Summarized details of Loans
Total Past Due	19,164	18,697
Commercial real estate — investor | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Summarized details of Loans
Total Past Due	0	19,432
Real estate construction
Summarized details of Loans
Current	2,285,763	2,271,392
Financing Receivable, Nonaccrual	18	6
Loans and Leases Receivable, Net of Deferred Income, Total	2,287,041	2,271,398
Real estate construction | 30-59 Days Past Due
Summarized details of Loans
Total Past Due	1,260	0
Real estate construction | 60-89 Days Past Due
Summarized details of Loans
Total Past Due	0	0
Real estate construction | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Summarized details of Loans
Total Past Due	0	0
Commercial real estate lending
Summarized details of Loans
Current	7,283,098	7,357,509
Financing Receivable, Nonaccrual	18,715	6
Loans and Leases Receivable, Net of Deferred Income, Total	7,322,237	7,395,644
Commercial real estate lending | 30-59 Days Past Due
Summarized details of Loans
Total Past Due	1,260	0
Commercial real estate lending | 60-89 Days Past Due
Summarized details of Loans
Total Past Due	19,164	18,697
Commercial real estate lending | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Summarized details of Loans
Total Past Due	0	19,432
Total commercial
Summarized details of Loans
Current	18,162,042	18,081,044
Financing Receivable, Nonaccrual	93,047	63,422
Loans and Leases Receivable, Net of Deferred Income, Total	18,276,460	18,188,898
Total commercial | 30-59 Days Past Due
Summarized details of Loans
Total Past Due	1,631	5,374
Total commercial | 60-89 Days Past Due
Summarized details of Loans
Total Past Due	19,314	19,246
Total commercial | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Summarized details of Loans
Total Past Due	426	19,812
Residential mortgage
Summarized details of Loans
Current	7,788,322	7,780,304
Financing Receivable, Nonaccrual	69,954	71,142
Loans and Leases Receivable, Net of Deferred Income, Total	7,868,180	7,864,891
Residential mortgage | 30-59 Days Past Due
Summarized details of Loans
Total Past Due	9,808	13,294
Residential mortgage | 60-89 Days Past Due
Summarized details of Loans
Total Past Due	94	152
Residential mortgage | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Summarized details of Loans
Total Past Due	0	0
Automobile Loan
Summarized details of Loans
Current	2,451,552	2,232,906
Financing Receivable, Nonaccrual	7,158	5,797
Loans and Leases Receivable, Net of Deferred Income, Total	2,471,257	2,256,162
Automobile Loan | 30-59 Days Past Due
Summarized details of Loans
Total Past Due	10,373	14,712
Automobile Loan | 60-89 Days Past Due
Summarized details of Loans
Total Past Due	2,148	2,674
Automobile Loan | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Summarized details of Loans
Total Past Due	26	73
Home equity
Summarized details of Loans
Current	608,821	615,810
Financing Receivable, Nonaccrual	8,100	8,508
Loans and Leases Receivable, Net of Deferred Income, Total	619,764	628,526
Home equity | 30-59 Days Past Due
Summarized details of Loans
Total Past Due	2,506	3,500
Home equity | 60-89 Days Past Due
Summarized details of Loans
Total Past Due	312	708
Home equity | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Summarized details of Loans
Total Past Due	24	0
Other consumer
Summarized details of Loans
Current	254,313	273,644
Financing Receivable, Nonaccrual	87	128
Loans and Leases Receivable, Net of Deferred Income, Total	258,603	277,740
Other consumer | 30-59 Days Past Due
Summarized details of Loans
Total Past Due	1,298	1,233
Other consumer | 60-89 Days Past Due
Summarized details of Loans
Total Past Due	963	932
Other consumer | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Summarized details of Loans
Total Past Due	1,942	1,803
Total consumer
Summarized details of Loans
Current	11,103,009	10,902,664
Financing Receivable, Nonaccrual	85,299	85,574
Loans and Leases Receivable, Net of Deferred Income, Total	11,217,802	11,027,319
Total consumer | 30-59 Days Past Due
Summarized details of Loans
Total Past Due	23,985	32,739
Total consumer | 60-89 Days Past Due
Summarized details of Loans
Total Past Due	3,517	4,467
Total consumer | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Summarized details of Loans
Total Past Due	$ 1,992	$ 1,876