Loans and Leases (Loans and Leases) (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases	$ 39,239.1	$ 40,480.6
Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases	19,224.7	18,487.4
Commercial | Commercial and Institutional
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases	11,756.6	11,489.2
Commercial | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases	4,295.2	4,326.3
Commercial | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases	2,655.0	1,990.2
Commercial | Lease Financing, net
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases	11.0	11.0
Commercial | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases	506.9	670.7
Personal
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases	20,014.4	21,993.2
Personal | Private Client
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases	13,280.5	15,256.3
Personal | Residential Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases	6,220.2	6,319.9
Personal | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases	496.6	381.8
Personal | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases	$ 17.1	$ 35.2