Loans and Leases (COVID-19 Loan Modifications Not Considered TDRS) (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021 contract	Sep. 30, 2020 contract	Sep. 30, 2021 USD ($) contract	Sep. 30, 2020 contract
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	1	11	16	19
CARES Act | Active Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			14,000,000
RECORDED INVESTMENT			$ 3.2
UNPAID PRINCIPAL BALANCE			0.1
DEFERRED INTEREST AMOUNT			$ 0.1
CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			555,000,000
RECORDED INVESTMENT			$ 883.9
UNPAID PRINCIPAL BALANCE			1.4
DEFERRED INTEREST AMOUNT			$ 6.7
Commercial
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	0	1	8	3
Commercial | CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			162,000,000
RECORDED INVESTMENT			$ 607.9
UNPAID PRINCIPAL BALANCE			0.0
DEFERRED INTEREST AMOUNT			$ 4.0
Commercial | Commercial and Institutional
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	0	1	6	3
Commercial | Commercial and Institutional | CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			79,000,000
RECORDED INVESTMENT			$ 211.6
UNPAID PRINCIPAL BALANCE			0.0
DEFERRED INTEREST AMOUNT			$ 1.7
Commercial | Commercial Real Estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	0		2
Commercial | Commercial Real Estate | CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			83,000,000
RECORDED INVESTMENT			$ 396.3
UNPAID PRINCIPAL BALANCE			0.0
DEFERRED INTEREST AMOUNT			$ 2.3
Personal
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	1	10	8	16
Personal | CARES Act | Active Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			14,000,000
RECORDED INVESTMENT			$ 3.2
UNPAID PRINCIPAL BALANCE			0.1
DEFERRED INTEREST AMOUNT			$ 0.1
Personal | CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			393,000,000
RECORDED INVESTMENT			$ 276.0
UNPAID PRINCIPAL BALANCE			1.4
DEFERRED INTEREST AMOUNT			$ 2.7
Personal | Private Client | CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			30,000,000
RECORDED INVESTMENT			$ 150.7
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	1	10	8	16
Personal | Residential Real Estate | CARES Act | Active Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			14,000,000
RECORDED INVESTMENT			$ 3.2
UNPAID PRINCIPAL BALANCE			0.1
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			363,000,000
RECORDED INVESTMENT			$ 125.3
UNPAID PRINCIPAL BALANCE			1.4
DEFERRED INTEREST AMOUNT			$ 1.7