Goodwill and Other Intangibles - Goodwill (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Goodwill [Roll Forward]
Beginning Balance	$ 691.3	$ 706.2
Foreign Exchange Rates	11.0	(14.9)
Ending Balance	702.3	691.3
ASSET SERVICING
Goodwill [Roll Forward]
Beginning Balance	611.0	625.7
Foreign Exchange Rates	10.9	(14.7)
Ending Balance	621.9	611.0
WEALTH MANAGEMENT
Goodwill [Roll Forward]
Beginning Balance	80.3	80.5
Foreign Exchange Rates	0.1	(0.2)
Ending Balance	$ 80.4	$ 80.3