v3.25.2
Fair Value Measurements (Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) - USD ($)
$ in Millions
Jun. 30, 2025
Dec. 31, 2024
Financial instruments owned:    
Exchange traded equity securities $ 22 $ 19
Fair Value, Measurements, Recurring    
Financial instruments owned:    
Exchange traded equity securities 11 7
Mutual funds 196 194
Unit investment trust 0 83
Money market funds 162 353
Total assets measured at fair value 369 637
Fiduciary Assets:    
Total fiduciary assets measured at fair value 243 76
Liabilities:    
Contingent purchase consideration liabilities 207 161
Total liabilities measured at fair value 207 161
Fair Value, Measurements, Recurring | Money market funds    
Fiduciary Assets:    
Total fiduciary assets measured at fair value 243 76
Identical Assets (Level 1) | Fair Value, Measurements, Recurring    
Financial instruments owned:    
Exchange traded equity securities 11 7
Mutual funds 196 194
Unit investment trust 0 0
Money market funds 162 353
Total assets measured at fair value 369 554
Fiduciary Assets:    
Total fiduciary assets measured at fair value 243 76
Liabilities:    
Contingent purchase consideration liabilities 0 0
Total liabilities measured at fair value 0 0
Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Money market funds    
Fiduciary Assets:    
Total fiduciary assets measured at fair value 243 76
Observable Inputs (Level 2) | Fair Value, Measurements, Recurring    
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 liabilities 0 0
Total liabilities measured at fair value 0 0
Observable Inputs (Level 2) | Fair Value, Measurements, Recurring | Money market funds    
Fiduciary Assets:    
Total fiduciary assets measured at fair value 0 0
Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring    
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 liabilities 207 161
Total liabilities measured at fair value 207 161
Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring | Money market funds    
Fiduciary Assets:    
Total fiduciary assets measured at fair value $ 0 $ 0