Goodwill and Other Intangibles (Goodwill by Reporting Segment) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2025 USD ($)
Goodwill [Roll Forward]
Goodwill, Beginning Balance	$ 694.9
Foreign Exchange Rates	5.6
Goodwill, Ending Balance	700.5
ASSET SERVICING
Goodwill [Roll Forward]
Goodwill, Beginning Balance	614.6
Foreign Exchange Rates	5.6
Goodwill, Ending Balance	620.2
WEALTH MANAGEMENT
Goodwill [Roll Forward]
Goodwill, Beginning Balance	80.3
Foreign Exchange Rates	0.0
Goodwill, Ending Balance	$ 80.3