Goodwill and Acquired Client Relationships - Schedule of Changes in Goodwill (Details) $ in Millions	9 Months Ended
	Sep. 30, 2023 USD ($)
Goodwill [Roll Forward]
Beginning balance	$ 2,648.7
Veritable Transaction	(136.5)
Foreign currency translation	1.9
Other	(5.1)
Ending balance	2,509.0
Schedule of Intangible Assets, by Major Class [Line Items]
Goodwill deconsolidated, attributable to non-controlling interest	136.5
Non- controlling Interests
Goodwill [Roll Forward]
Veritable Transaction	(3.5)
Schedule of Intangible Assets, by Major Class [Line Items]
Goodwill deconsolidated, attributable to non-controlling interest	$ 3.5