Goodwill and Other Intangible Assets - Goodwill (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Goodwill [Roll Forward]
Goodwill, Beginning Balance	$ 327.0	$ 72.0
Additions from business combinations	319.0	255.0
Goodwill, Ending Balance	646.0
Wealth
Goodwill [Roll Forward]
Goodwill, Beginning Balance	17.0	17.0
Additions from business combinations	0.0	0.0
Goodwill, Ending Balance	17.0
Health Solutions
Goodwill [Roll Forward]
Goodwill, Beginning Balance	24.0	24.0
Additions from business combinations	319.0	0.0
Goodwill, Ending Balance	343.0
Investment Management
Goodwill [Roll Forward]
Goodwill, Beginning Balance	286.0	31.0
Additions from business combinations	0.0	$ 255.0
Goodwill, Ending Balance	$ 286.0