Goodwill and Other Intangibles (Goodwill by Reporting Segment) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2025 USD ($)
Goodwill [Roll Forward]
Goodwill, Beginning Balance	$ 694.9
Foreign Exchange Rates	18.0
Goodwill, Ending Balance	712.9
ASSET SERVICING
Goodwill [Roll Forward]
Goodwill, Beginning Balance	614.6
Foreign Exchange Rates	17.9
Goodwill, Ending Balance	632.5
WEALTH MANAGEMENT
Goodwill [Roll Forward]
Goodwill, Beginning Balance	80.3
Foreign Exchange Rates	0.1
Goodwill, Ending Balance	$ 80.4