v3.26.1
Goodwill and Other Intangible Assets - Changes in the Net Carrying Amount of the Components of Finite-Lived Intangible Assets (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2025
Finite-lived Intangible Assets [Roll Forward]      
Finite-lived intangible assets, gross carrying amount $ 5,217   $ 5,059
Finite-lived intangible assets, accumulated amortization (3,942)   (3,918)
Finite-lived intangible assets, net amount 1,275   1,141
Intangible assets acquired 185    
Amortization (48) $ (48)  
Foreign exchange (3)    
Client relationships [Member]      
Finite-lived Intangible Assets [Roll Forward]      
Finite-lived intangible assets, gross carrying amount 3,349   3,239
Finite-lived intangible assets, accumulated amortization (2,727)   (2,710)
Finite-lived intangible assets, net amount 622   529
Intangible assets acquired 132    
Amortization (36)    
Foreign exchange (3)    
Software [Member]      
Finite-lived Intangible Assets [Roll Forward]      
Finite-lived intangible assets, gross carrying amount 798   750
Finite-lived intangible assets, accumulated amortization (746)   (749)
Finite-lived intangible assets, net amount 52   1
Intangible assets acquired 53    
Amortization (2)    
Foreign exchange 0    
Trademark and trade name [Member]      
Finite-lived Intangible Assets [Roll Forward]      
Finite-lived intangible assets, gross carrying amount 1,041   1,041
Finite-lived intangible assets, accumulated amortization (440)   (430)
Finite-lived intangible assets, net amount 601   611
Intangible assets acquired 0    
Amortization (10)    
Foreign exchange 0    
Other [Member]      
Finite-lived Intangible Assets [Roll Forward]      
Finite-lived intangible assets, gross carrying amount 29   29
Finite-lived intangible assets, accumulated amortization (29)   (29)
Finite-lived intangible assets, net amount 0   $ 0
Intangible assets acquired 0    
Amortization 0    
Foreign exchange $ 0