Loans and Leases (COVID-19 Loan Modifications Not Considered TDRS) (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020 contract	Jun. 30, 2019 contract	Jun. 30, 2020 USD ($) contract	Jun. 30, 2019 contract
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	0	15	8	29
CARES Act
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			783,000,000
RECORDED INVESTMENT			$ 1,157.8
UNPAID PRINCIPAL BALANCE			9.3
DEFERRED INTEREST AMOUNT			$ 7.4
COMMERCIAL
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	0	2	2	3
COMMERCIAL | CARES Act
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			227,000,000
RECORDED INVESTMENT			$ 757.1
UNPAID PRINCIPAL BALANCE			6.5
DEFERRED INTEREST AMOUNT			$ 4.3
COMMERCIAL | Commercial and Institutional
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	0	0	2	1
COMMERCIAL | Commercial and Institutional | CARES Act
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			119,000,000
RECORDED INVESTMENT			$ 275.5
UNPAID PRINCIPAL BALANCE			4.3
DEFERRED INTEREST AMOUNT			$ 1.5
COMMERCIAL | Commercial Real Estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract		2		2
COMMERCIAL | Commercial Real Estate | CARES Act
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			108,000,000
RECORDED INVESTMENT			$ 481.6
UNPAID PRINCIPAL BALANCE			2.2
DEFERRED INTEREST AMOUNT			$ 2.8
Personal
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	0	13	6	26
Personal | CARES Act
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			556,000,000
RECORDED INVESTMENT			$ 400.7
UNPAID PRINCIPAL BALANCE			2.8
DEFERRED INTEREST AMOUNT			$ 3.1
Personal | Private Client | CARES Act
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			34,000,000
RECORDED INVESTMENT			$ 174.8
UNPAID PRINCIPAL BALANCE			1.7
DEFERRED INTEREST AMOUNT			$ 0.9
Personal | Residential Real Estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	0	13	6	26
Personal | Residential Real Estate | CARES Act
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			522,000,000
RECORDED INVESTMENT			$ 225.9
UNPAID PRINCIPAL BALANCE			1.1
DEFERRED INTEREST AMOUNT			$ 2.2