Revenue from Contracts with Clients (Revenue Disaggregated by Major Source) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Trust, Investment and Other Servicing Fees	$ 4,432.6	$ 4,361.1	$ 3,995.0
Foreign Exchange Trading Income	288.6	292.6	290.4
Treasury Management Fees	39.3	44.3	45.4
Security Commissions and Trading Income	136.2	140.2	133.2
Other Operating Income	191.3	243.9	194.0
Investment Security Gains (Losses), net	(214.0)	(0.3)	(0.4)
Total Other Noninterest Income	441.4	720.7	662.6
Total Noninterest Income	4,874.0	5,081.8	4,657.6
Custody and Fund Administration
Disaggregation of Revenue [Line Items]
Trust, Investment and Other Servicing Fees	1,816.0	1,917.5	1,674.3
Investment Management and Advisory
Disaggregation of Revenue [Line Items]
Trust, Investment and Other Servicing Fees	2,299.1	2,140.0	2,029.3
Securities Lending
Disaggregation of Revenue [Line Items]
Trust, Investment and Other Servicing Fees	81.6	76.9	88.3
Other
Disaggregation of Revenue [Line Items]
Trust, Investment and Other Servicing Fees	$ 235.9	$ 226.7	$ 203.1