Loans and Leases (COVID-19 Loan Modifications Not Considered TDRS) (Details) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2022 USD ($) contract	Mar. 31, 2021 contract	Dec. 31, 2021 USD ($) contract
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	3	9
CARES Act | Active Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	356,000,000		3
RECORDED INVESTMENT	$ 707.5		$ 2.0
UNPAID PRINCIPAL BALANCE	1.0
DEFERRED INTEREST AMOUNT	$ 5.4
CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			390,000,000
RECORDED INVESTMENT			$ 835.6
UNPAID PRINCIPAL BALANCE			1.2
DEFERRED INTEREST AMOUNT			$ 6.3
Commercial
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	1	7
Commercial | CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	136,000,000		153,000,000
RECORDED INVESTMENT	$ 499.6		$ 590.5
UNPAID PRINCIPAL BALANCE	0.0		0.1
DEFERRED INTEREST AMOUNT	$ 3.4		$ 4.0
Commercial | Commercial and Institutional
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	1	6
Commercial | Commercial and Institutional | CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	62,000,000		73,000,000
RECORDED INVESTMENT	$ 148.6		$ 199.8
UNPAID PRINCIPAL BALANCE	0.0		0.1
DEFERRED INTEREST AMOUNT	$ 1.1		$ 1.6
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	74,000,000		80,000,000
RECORDED INVESTMENT	$ 351.0		$ 390.7
UNPAID PRINCIPAL BALANCE	0.0		0.0
DEFERRED INTEREST AMOUNT	$ 2.3		$ 2.4
Personal
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	2	2
Personal | CARES Act | Active Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	220,000,000
RECORDED INVESTMENT	$ 207.9
UNPAID PRINCIPAL BALANCE	1.0
DEFERRED INTEREST AMOUNT	$ 2.0
Personal | CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			237,000,000
RECORDED INVESTMENT			$ 245.1
UNPAID PRINCIPAL BALANCE			1.1
DEFERRED INTEREST AMOUNT			$ 2.3
Personal | Private Client | CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	22,000,000		29,000,000
RECORDED INVESTMENT	$ 116.9		$ 143.1
UNPAID PRINCIPAL BALANCE	0.0		0.0
DEFERRED INTEREST AMOUNT	$ 0.8		$ 1.0
Personal | Residential Real Estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	2	2
Personal | Residential Real Estate | CARES Act | Active Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract	198,000,000
RECORDED INVESTMENT	$ 91.0
UNPAID PRINCIPAL BALANCE	1.0
DEFERRED INTEREST AMOUNT	$ 1.2
Personal | Residential Real Estate | CARES Act | Completed Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES | contract			208,000,000
RECORDED INVESTMENT			$ 102.0
UNPAID PRINCIPAL BALANCE			1.1
DEFERRED INTEREST AMOUNT			$ 1.3