Loans and Leases (Loans and Leases) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases	$ 40,480.6	$ 33,759.7
Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases	4,326.3	3,558.4
Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases	18,487.4	15,262.0
Commercial | Commercial and Institutional
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases	11,489.2	10,058.3
Commercial | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases	4,326.3	3,558.4
Commercial | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases	1,990.2	1,345.7
Commercial | Lease Financing, net
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases	11.0	11.4
Commercial | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases	670.7	288.2
Personal
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases	21,993.2	18,497.7
Personal | Private Client
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases	15,256.3	11,815.1
Personal | Residential Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases	6,319.9	6,035.7
Personal | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases	381.8	597.9
Personal | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans and leases	$ 35.2	$ 49.0