v3.26.1
Other assets - Seed Capital and Private Equity Investments (Details) - NAV - USD ($)
$ in Millions
 6 Months Ended
Jun. 30, 2026
Dec. 31, 2025
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Line Items]    
Fair value $ 154 $ 155
Unfunded commitments 93 75
Seed capital    
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Line Items]    
Fair value 9 6
Unfunded commitments $ 0 0
Fair value, investments, entities that calculate net asset value per share, liquidating investment, remaining period 7 days  
Private equity investments    
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Line Items]    
Fair value $ 140 139
Unfunded commitments $ 93 75
Fair value, investments, entities that calculate net asset value per share, liquidating investment, remaining period 10 years  
Other    
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Line Items]    
Fair value $ 5 10
Unfunded commitments $ 0 $ 0