Loans (Loans) (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases	$ 43,546.7	$ 42,893.3
Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases	22,361.2	21,635.6
Commercial | Commercial and Institutional
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases	12,239.0	12,415.0
Commercial | Commercial and Institutional | Private Equity Funds
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases	5,200.0	5,600.0
Commercial | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases	5,040.1	4,773.0
Commercial | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases	2,833.7	3,131.1
Commercial | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases	2,248.4	1,316.5
Personal
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases	21,185.5	21,257.7
Personal | Private Client
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases	14,172.3	14,119.0
Personal | Residential Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases	6,357.9	6,413.5
Personal | Non-U.S.
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases	415.0	510.0
Personal | Other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases	$ 240.3	$ 215.2