Goodwill and Other Intangibles (Goodwill by Reporting Segment) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2024 USD ($)
Goodwill [Roll Forward]
Goodwill, Beginning Balance	$ 702.3
Foreign Exchange Rates	5.5
Goodwill, Ending Balance	707.8
ASSET SERVICING
Goodwill [Roll Forward]
Goodwill, Beginning Balance	621.9
Foreign Exchange Rates	5.5
Goodwill, Ending Balance	627.4
WEALTH MANAGEMENT
Goodwill [Roll Forward]
Goodwill, Beginning Balance	80.4
Foreign Exchange Rates	0.0
Goodwill, Ending Balance	$ 80.4