Goodwill and Other Intangibles (Goodwill by Reporting Segment) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2024 USD ($)
Goodwill [Roll Forward]
Goodwill, Beginning Balance	$ 702.3
Foreign Exchange Rates	(4.9)
Goodwill, Ending Balance	697.4
ASSET SERVICING
Goodwill [Roll Forward]
Goodwill, Beginning Balance	621.9
Foreign Exchange Rates	(4.8)
Goodwill, Ending Balance	617.1
WEALTH MANAGEMENT
Goodwill [Roll Forward]
Goodwill, Beginning Balance	80.4
Foreign Exchange Rates	(0.1)
Goodwill, Ending Balance	$ 80.3