Goodwill and Other Intangibles - Goodwill (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Goodwill [Roll Forward]
Beginning Balance	$ 702.3	$ 691.3
Foreign Exchange Rates	(7.4)	11.0
Ending Balance	694.9	702.3
ASSET SERVICING
Goodwill [Roll Forward]
Beginning Balance	621.9	611.0
Foreign Exchange Rates	(7.3)	10.9
Ending Balance	614.6	621.9
WEALTH MANAGEMENT
Goodwill [Roll Forward]
Beginning Balance	80.4	80.3
Foreign Exchange Rates	(0.1)	0.1
Ending Balance	$ 80.3	$ 80.4