Loans and Allowance for Credit Losses Past Due Loan Status and Non-Accrual Loans by Portfolio Segment (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Financing Receivable, Past Due [Line Items]
Non- accrual	$ 162,530	$ 143,666
Total	18,920,950	18,325,350
Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	65,621	38,977
Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	13,437	8,659
Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	11,016	8,453
Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total	18,668,346	18,125,595
Real estate - commercial mortgage
Financing Receivable, Past Due [Line Items]
Non- accrual	59,565	52,815
Total	7,417,036	7,279,080
Real estate - commercial mortgage \| Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	5,486	1,089
Real estate - commercial mortgage \| Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	3,219	1,750
Real estate - commercial mortgage \| Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	375	1,229
Real estate - commercial mortgage \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total	7,348,391	7,222,197
Commercial and Industrial
Financing Receivable, Past Due [Line Items]
Non- accrual	43,691	30,141
Total	4,173,114	4,208,327
Commercial and Industrial \| Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	11,197	5,457
Commercial and Industrial \| Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	1,417	1,932
Commercial and Industrial \| Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	1,022	488
Commercial and Industrial \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total	4,115,787	4,170,309
Real estate - residential mortgage
Financing Receivable, Past Due [Line Items]
Non- accrual	35,585	35,269
Total	4,203,827	3,846,750
Real estate - residential mortgage \| Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	31,221	22,957
Real estate - residential mortgage \| Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	5,796	2,920
Real estate - residential mortgage \| Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	7,337	4,130
Real estate - residential mortgage \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total	4,123,888	3,781,474
Real-estate - home equity
Financing Receivable, Past Due [Line Items]
Non- accrual	8,110	8,671
Total	1,108,808	1,118,248
Real-estate - home equity \| Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	4,554	4,369
Real-estate - home equity \| Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	1,341	1,154
Real-estate - home equity \| Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	1,942	2,253
Real-estate - home equity \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total	1,092,861	1,101,801
Real-estate - construction
Financing Receivable, Past Due [Line Items]
Non- accrual	1,357	901
Total	1,177,446	1,139,779
Real-estate - construction \| Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	3,728	1,318
Real-estate - construction \| Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	550	0
Real-estate - construction \| Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	0	0
Real-estate - construction \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total	1,171,811	1,137,560
Consumer
Financing Receivable, Past Due [Line Items]
Non- accrual	160	229
Total	538,747	464,657
Consumer \| Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	4,963	3,561
Consumer \| Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	1,081	876
Consumer \| Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	340	353
Consumer \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total	532,203	459,638
Equipment lease financing, other and overdrafts
Financing Receivable, Past Due [Line Items]
Non- accrual	14,062	15,640
Total	301,972	268,509
Equipment lease financing, other and overdrafts \| Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	4,472	226
Equipment lease financing, other and overdrafts \| Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	33	27
Equipment lease financing, other and overdrafts \| Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	0	0
Equipment lease financing, other and overdrafts \| Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total	283,405	$ 252,616
US Government Insured Loan Program \| Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	7,900
US Government Insured Loan Program \| Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	1,300
US Government Insured Loan Program \| Financial Asset, Equal to or Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	$ 700