Goodwill and Other Intangibles - Goodwill (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Goodwill [Roll Forward]
Beginning Balance	$ 694.9	$ 702.3
Foreign Exchange Rates	18.0	(7.4)
Ending Balance	712.9	694.9
ASSET SERVICING
Goodwill [Roll Forward]
Beginning Balance	614.6	621.9
Foreign Exchange Rates	17.9	(7.3)
Ending Balance	632.5	614.6
WEALTH MANAGEMENT
Goodwill [Roll Forward]
Beginning Balance	80.3	80.4
Foreign Exchange Rates	0.1	(0.1)
Ending Balance	$ 80.4	$ 80.3