Goodwill and Other Intangibles (Goodwill by Reporting Segment) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2023 USD ($)
Goodwill [Roll Forward]
Goodwill, Beginning Balance	$ 691.3
Foreign Exchange Rates	1.5
Goodwill, Ending Balance	692.8
ASSET SERVICING
Goodwill [Roll Forward]
Goodwill, Beginning Balance	611.0
Foreign Exchange Rates	1.5
Goodwill, Ending Balance	612.5
WEALTH MANAGEMENT
Goodwill [Roll Forward]
Goodwill, Beginning Balance	80.3
Foreign Exchange Rates	0.0
Goodwill, Ending Balance	$ 80.3