Loans and Leases (COVID-19 Loan Modifications Not Considered TDRS) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2021 USD ($) contract	Mar. 31, 2020 contract
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	9	8
CARES Act | Active Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	25,000,000
RECORDED INVESTMENT	$ 9.5
UNPAID PRINCIPAL BALANCE	0.2
DEFERRED INTEREST AMOUNT	$ 0.2
CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	595,000,000
RECORDED INVESTMENT	$ 1,030.2
UNPAID PRINCIPAL BALANCE	1.4
DEFERRED INTEREST AMOUNT	$ 8.4
Commercial
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	7	2
Commercial | CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	181,000,000
RECORDED INVESTMENT	$ 695.6
UNPAID PRINCIPAL BALANCE	0.0
DEFERRED INTEREST AMOUNT	$ 5.2
Commercial | Commercial and Institutional
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	6	2
Commercial | Commercial and Institutional | CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	90,000,000
RECORDED INVESTMENT	$ 238.4
UNPAID PRINCIPAL BALANCE	0.0
DEFERRED INTEREST AMOUNT	$ 2.0
Commercial | Commercial Real Estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	1
Commercial | Commercial Real Estate | CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	91,000,000
RECORDED INVESTMENT	$ 457.2
UNPAID PRINCIPAL BALANCE	0.0
DEFERRED INTEREST AMOUNT	$ 3.2
Personal
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	2	6
Personal | CARES Act | Active Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	25,000,000
RECORDED INVESTMENT	$ 9.5
UNPAID PRINCIPAL BALANCE	0.2
DEFERRED INTEREST AMOUNT	$ 0.2
Personal | CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	414,000,000
RECORDED INVESTMENT	$ 334.6
UNPAID PRINCIPAL BALANCE	1.4
DEFERRED INTEREST AMOUNT	$ 3.2
Personal | Private Client | CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	32,000,000
RECORDED INVESTMENT	$ 169.8
UNPAID PRINCIPAL BALANCE	0.0
DEFERRED INTEREST AMOUNT	$ 1.2
Personal | Residential Real Estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	2	6
Personal | Residential Real Estate | CARES Act | Active Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	25,000,000
RECORDED INVESTMENT	$ 9.5
UNPAID PRINCIPAL BALANCE	0.2
DEFERRED INTEREST AMOUNT	$ 0.2
Personal | Residential Real Estate | CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	382,000,000
RECORDED INVESTMENT	$ 164.8
UNPAID PRINCIPAL BALANCE	1.4
DEFERRED INTEREST AMOUNT	$ 2.0