v3.25.4
Fair Value Measurements (Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) - USD ($)
$ in Millions
Dec. 31, 2025
Dec. 31, 2024
Financial instruments owned:    
Exchange traded equity securities $ 12 $ 7
Mutual funds 202 194
Unit investment trust 0 83
Money market funds 633 353
Total assets measured at fair value 847 637
Fiduciary Assets:    
Total fiduciary assets measured at fair value 322 76
Liabilities:    
Contingent purchase consideration liability 268 161
Total liabilities measured at fair value 268 161
Identical Assets (Level 1)    
Financial instruments owned:    
Exchange traded equity securities 12 7
Mutual funds 202 194
Unit investment trust 0 0
Money market funds 633 353
Total assets measured at fair value 847 554
Fiduciary Assets:    
Total fiduciary assets measured at fair value 322 76
Liabilities:    
Contingent purchase consideration liability 0 0
Total liabilities measured at fair value 0 0
Observable Inputs (Level 2)    
Financial instruments owned:    
Exchange traded equity securities 0 0
Mutual funds 0 0
Unit investment trust 0 83
Money market funds 0 0
Total assets measured at fair value 0 83
Fiduciary Assets:    
Total fiduciary assets measured at fair value 0 0
Liabilities:    
Contingent purchase consideration liability 0 0
Total liabilities measured at fair value 0 0
Unobservable Inputs (Level 3)    
Financial instruments owned:    
Exchange traded equity securities 0 0
Mutual funds 0 0
Unit investment trust 0 0
Money market funds 0 0
Total assets measured at fair value 0 0
Fiduciary Assets:    
Total fiduciary assets measured at fair value 0 0
Liabilities:    
Contingent purchase consideration liability 268 161
Total liabilities measured at fair value 268 161
Money market funds    
Fiduciary Assets:    
Total fiduciary assets measured at fair value 322 76
Money market funds | Identical Assets (Level 1)    
Fiduciary Assets:    
Total fiduciary assets measured at fair value 322 76
Money market funds | Observable Inputs (Level 2)    
Fiduciary Assets:    
Total fiduciary assets measured at fair value 0 0
Money market funds | Unobservable Inputs (Level 3)    
Fiduciary Assets:    
Total fiduciary assets measured at fair value $ 0 $ 0