Allowance for Credit Losses - Past-Due Status (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Financing Receivable, Recorded Investment, Past Due
Loans and leases	$ 14,241,370	$ 14,353,497
Loans and Leases Past Due 90 Days or More and Still Accruing Interest	4,543	3,496
Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	38,539	62,245
Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	9,516	6,541
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	14,531	12,736
Financial Asset, Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	62,586	81,522
Financial Asset, Not Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	14,178,784	14,271,975
Commercial and Industrial
Financing Receivable, Recorded Investment, Past Due
Loans and leases	2,110,077	2,165,349
Loans and Leases Past Due 90 Days or More and Still Accruing Interest	529	494
Commercial and Industrial | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	2,118	2,611
Commercial and Industrial | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	670	349
Commercial and Industrial | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	1,463	1,464
Commercial and Industrial | Financial Asset, Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	4,251	4,424
Commercial and Industrial | Financial Asset, Not Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	2,105,826	2,160,925
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	4,265,289	4,340,243
Loans and Leases Past Due 90 Days or More and Still Accruing Interest	568	300
Commercial Real Estate Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	246	196
Commercial Real Estate Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	720	300
Commercial Real Estate Portfolio Segment [Member] | Financial Asset, Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	966	496
Commercial Real Estate Portfolio Segment [Member] | Financial Asset, Not Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	4,264,323	4,339,747
Construction
Financing Receivable, Recorded Investment, Past Due
Loans and leases	1,056,249	900,292
Construction | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	1,179	25,191
Construction | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	139
Construction | Financial Asset, Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	1,318	25,191
Construction | Financial Asset, Not Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	1,054,931	875,101
Finance Leases Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	432,828	379,809
Finance Leases Portfolio Segment [Member] | Financial Asset, Not Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	432,828	379,809
Residential mortgage
Financing Receivable, Recorded Investment, Past Due
Loans and leases	5,346,883
Consumer
Financing Receivable, Recorded Investment, Past Due
Loans and leases	1,030,044	1,109,901
Loans and Leases Past Due 90 Days or More and Still Accruing Interest	2,515	2,702
Consumer | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	15,227	23,259
Consumer | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	2,939	3,897
Consumer | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	2,515	2,702
Consumer | Financial Asset, Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	20,681	29,858
Consumer | Financial Asset, Not Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	1,009,363	1,080,043
Real Estate Loan [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	4,187,060	4,283,315
Real Estate Loan [Member] | Residential mortgage
Financing Receivable, Recorded Investment, Past Due
Loans and leases	4,187,060	4,283,315
Loans and Leases Past Due 90 Days or More and Still Accruing Interest	931
Real Estate Loan [Member] | Residential mortgage | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	15,356	5,244
Real Estate Loan [Member] | Residential mortgage | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	4,631	1,475
Real Estate Loan [Member] | Residential mortgage | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	6,425	4,720
Real Estate Loan [Member] | Residential mortgage | Financial Asset, Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	26,412	11,439
Real Estate Loan [Member] | Residential mortgage | Financial Asset, Not Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	4,160,648	4,271,876
Residential Lending: Home Equity Line
Financing Receivable, Recorded Investment, Past Due
Loans and leases	1,159,823	1,174,588
Residential Lending: Home Equity Line | Home equity Line
Financing Receivable, Recorded Investment, Past Due
Loans and leases	1,159,823	1,174,588
Residential Lending: Home Equity Line | Home equity Line | Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	4,659	5,940
Residential Lending: Home Equity Line | Home equity Line | Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	891	624
Residential Lending: Home Equity Line | Home equity Line | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	3,408	3,550
Residential Lending: Home Equity Line | Home equity Line | Financial Asset, Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	8,958	10,114
Residential Lending: Home Equity Line | Home equity Line | Financial Asset, Not Past Due [Member]
Financing Receivable, Recorded Investment, Past Due
Loans and leases	$ 1,150,865	$ 1,164,474