Acquisitions - Summary of Preliminary Purchase Price allocation (Details) - USD ($)
$ in Millions
Dec. 31, 2021
Oct. 01, 2021
Jul. 02, 2021
Jul. 01, 2021
Jun. 30, 2021
Dec. 31, 2020
Business Acquisition [Line Items]            
Goodwill $ 3,638     $ 3,383 $ 2,250 $ 2,245
Foley Trasimene Acquisition Corp            
Business Acquisition [Line Items]            
Cash and cash equivalents     $ 460      
Receivables     486      
Fiduciary assets     1,015      
Other current assets     162      
Fixed assets     205      
Other assets     425      
Accounts payable and accrued liabilities     (327)      
Fiduciary liabilities     (1,015)      
Other current liabilities     (293)      
Debt assumed     (2,370)      
Deferred tax liabilities     (3)      
Other liabilities     (396)      
Intangible assets     4,078      
Total identifiable net assets     2,427      
Goodwill     $ 3,383      
Retiree Health Exchange            
Business Acquisition [Line Items]            
Receivables   $ 1        
Other current assets   29        
Accounts payable and accrued liabilities   (13)        
Intangible assets   104        
Total identifiable net assets   121        
Goodwill   78        
Total consideration   $ 199