Loans and Allowance for Credit Losses Past Due Loan Status and Non-Accrual Loans by Portfolio Segment (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Past Due [Line Items]
≥ 90 Days Past Due and Accruing	$ 8,453	$ 9,929
Non- accrual	143,666	137,198
Net Loans	18,325,350	18,900,820
Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	38,977	59,999
Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	8,659	20,321
Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total	18,125,595	18,673,373
Real estate - commercial mortgage
Financing Receivable, Past Due [Line Items]
≥ 90 Days Past Due and Accruing	1,229	1,177
Non- accrual	52,815	51,470
Net Loans	7,279,080	7,105,092
Real estate - commercial mortgage | Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	1,089	14,999
Real estate - commercial mortgage | Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	1,750	9,273
Real estate - commercial mortgage | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total	7,222,197	7,028,173
Commercial and industrial
Financing Receivable, Past Due [Line Items]
≥ 90 Days Past Due and Accruing	488	616
Non- accrual	30,141	31,993
Net Loans	4,208,327	5,670,828
Commercial and industrial | Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	5,457	11,285
Commercial and industrial | Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	1,932	1,068
Commercial and industrial | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total	4,170,309	5,625,866
Real estate - residential mortgage
Financing Receivable, Past Due [Line Items]
≥ 90 Days Past Due and Accruing	4,130	4,687
Non- accrual	35,269	26,107
Net Loans	3,846,750	3,141,915
Real estate - residential mortgage | Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	22,957	22,281
Real estate - residential mortgage | Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	2,920	7,675
Real estate - residential mortgage | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total	3,781,474	3,081,165
Real estate - home equity
Financing Receivable, Past Due [Line Items]
≥ 90 Days Past Due and Accruing	2,253	2,753
Non- accrual	8,671	9,588
Net Loans	1,118,248	1,202,913
Real estate - home equity | Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	4,369	5,622
Real estate - home equity | Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	1,154	1,654
Real estate - home equity | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total	1,101,801	1,183,296
Real-estate - construction
Financing Receivable, Past Due [Line Items]
≥ 90 Days Past Due and Accruing	0	155
Non- accrual	901	1,395
Net Loans	1,139,779	1,047,218
Real-estate - construction | Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	1,318	1,938
Real-estate - construction | Financial Asset, 60 to 89 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	1,137,560	1,043,730
Consumer
Financing Receivable, Past Due [Line Items]
≥ 90 Days Past Due and Accruing	353	417
Non- accrual	229	332
Net Loans	464,657	466,772
Consumer | Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	3,561	3,036
Consumer | Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	876	501
Consumer | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total	459,638	462,486
Equipment lease financing and other
Financing Receivable, Past Due [Line Items]
≥ 90 Days Past Due and Accruing	0	124
Non- accrual	15,640	16,313
Net Loans	268,509	266,082
Equipment lease financing and other | Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	226	838
Equipment lease financing and other | Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total	27	150
Equipment lease financing and other | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Total	$ 252,616	$ 248,657