Loans and Allowance for Credit Losses Past Due Loan Status and Non-Accrual Loans by Portfolio Segment (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Financing Receivable, Past Due [Line Items]
Total	$ 24,041,489	$ 24,044,919
Non- accrual	150,137	189,293
Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	134,379	115,714
Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	21,519	34,218
Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	48,597	30,781
Current
Financing Receivable, Past Due [Line Items]
Total	23,686,857	23,674,913
Real estate - commercial mortgage
Financing Receivable, Past Due [Line Items]
Total	9,734,156	9,601,858
Non- accrual	69,980	99,497
Real estate - commercial mortgage \| Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	55,724	32,715
Real estate - commercial mortgage \| Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	8,949	16,684
Real estate - commercial mortgage \| Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	17,809	2,862
Real estate - commercial mortgage \| Current
Financing Receivable, Past Due [Line Items]
Total	9,581,694	9,450,100
Commercial and Industrial
Financing Receivable, Past Due [Line Items]
Total	4,437,905	4,605,589
Non- accrual	42,468	42,217
Commercial and Industrial \| Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	15,591	6,031
Commercial and Industrial \| Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	1,394	3,636
Commercial and Industrial \| Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	6,349	1,460
Commercial and Industrial \| Current
Financing Receivable, Past Due [Line Items]
Total	4,372,103	4,552,245
Real estate - residential mortgage
Financing Receivable, Past Due [Line Items]
Total	6,617,017	6,349,643
Non- accrual	27,419	25,400
Real estate - residential mortgage \| Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	51,012	59,593
Real estate - residential mortgage \| Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	8,537	5,946
Real estate - residential mortgage \| Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	17,270	20,501
Real estate - residential mortgage \| Current
Financing Receivable, Past Due [Line Items]
Total	6,512,779	6,238,203
Real estate - home equity
Financing Receivable, Past Due [Line Items]
Total	1,214,399	1,160,616
Non- accrual	6,891	8,591
Real estate - home equity \| Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	5,297	6,778
Real estate - home equity \| Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	703	1,057
Real estate - home equity \| Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	4,766	4,758
Real estate - home equity \| Current
Financing Receivable, Past Due [Line Items]
Total	1,196,742	1,139,432
Real-estate - construction
Financing Receivable, Past Due [Line Items]
Total	1,134,748	1,394,899
Non- accrual	2,073	1,746
Real-estate - construction \| Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	1,026	3,549
Real-estate - construction \| Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	0	5,163
Real-estate - construction \| Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	1,388	0
Real-estate - construction \| Current
Financing Receivable, Past Due [Line Items]
Total	1,130,261	1,384,441
Consumer
Financing Receivable, Past Due [Line Items]
Total	566,291	616,856
Non- accrual	4	8
Consumer \| Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	5,606	6,779
Consumer \| Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	1,706	1,627
Consumer \| Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	997	1,017
Consumer \| Current
Financing Receivable, Past Due [Line Items]
Total	557,978	607,425
Leases and other loans
Financing Receivable, Past Due [Line Items]
Total	336,973	315,458
Non- accrual	1,302	11,834
Leases and other loans \| Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	123	269
Leases and other loans \| Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	230	105
Leases and other loans \| Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	18	183
Leases and other loans \| Current
Financing Receivable, Past Due [Line Items]
Total	$ 335,300	$ 303,067