Loans and Leases (COVID-19 Loan Modifications Not Considered TDRS) (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021 contract	Jun. 30, 2020 contract	Jun. 30, 2021 USD ($) contract	Jun. 30, 2020 contract
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	6	0	15	8
CARES Act | Active Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			13,000,000
RECORDED INVESTMENT			$ 4.7
UNPAID PRINCIPAL BALANCE			0.2
DEFERRED INTEREST AMOUNT			$ 0.1
CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			579,000,000
RECORDED INVESTMENT			$ 969.6
UNPAID PRINCIPAL BALANCE			1.5
DEFERRED INTEREST AMOUNT			$ 7.2
Commercial
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	1	0	8	2
Commercial | CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			172,000,000
RECORDED INVESTMENT			$ 670.4
UNPAID PRINCIPAL BALANCE			0.0
DEFERRED INTEREST AMOUNT			$ 4.4
Commercial | Commercial and Institutional
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	0	0	6	2
Commercial | Commercial and Institutional | CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			84,000,000
RECORDED INVESTMENT			$ 226.7
UNPAID PRINCIPAL BALANCE			0.0
DEFERRED INTEREST AMOUNT			$ 1.8
Commercial | Commercial Real Estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	1		2
Commercial | Commercial Real Estate | CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			88,000,000
RECORDED INVESTMENT			$ 443.7
UNPAID PRINCIPAL BALANCE			0.0
DEFERRED INTEREST AMOUNT			$ 2.6
Personal
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	5	0	7	6
Personal | CARES Act | Active Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			13,000,000
RECORDED INVESTMENT			$ 4.7
UNPAID PRINCIPAL BALANCE			0.2
DEFERRED INTEREST AMOUNT			$ 0.1
Personal | CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			407,000,000
RECORDED INVESTMENT			$ 299.2
UNPAID PRINCIPAL BALANCE			1.5
DEFERRED INTEREST AMOUNT			$ 2.8
Personal | Private Client | CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			31,000,000
RECORDED INVESTMENT			$ 153.0
UNPAID PRINCIPAL BALANCE			0.0
DEFERRED INTEREST AMOUNT			$ 1.0
Personal | Residential Real Estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	5	0	7	6
Personal | Residential Real Estate | CARES Act | Active Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			13,000,000
RECORDED INVESTMENT			$ 4.7
UNPAID PRINCIPAL BALANCE			0.2
DEFERRED INTEREST AMOUNT			$ 0.1
Personal | Residential Real Estate | CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			376,000,000
RECORDED INVESTMENT			$ 146.2
UNPAID PRINCIPAL BALANCE			1.5
DEFERRED INTEREST AMOUNT			$ 1.8