v3.26.3
Commitments, contingencies, and guarantees Commitments, Contingencies, And Guarantees (Collateral pledged under repurchase agreements) (Details) - USD ($)
$ in Millions
Sep. 30, 2026
Dec. 31, 2025
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Repurchase agreements $ 3,225 $ 3,324
Securities Sold under Agreements to Repurchase 3,225 3,324
Securities Sold under Agreements to Repurchase    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Repurchase agreements 3,225 3,324
Asset Pledged as Collateral without Right    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Assets pledged under repurchase agreements 3,434 3,518
Cash [Member] | Asset Pledged as Collateral without Right    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Assets pledged under repurchase agreements 3 0
Non-US [Member] | Asset Pledged as Collateral without Right    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Assets pledged under repurchase agreements 1,429 1,496
U.S. and local government securities | Asset Pledged as Collateral without Right    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Assets pledged under repurchase agreements 41 129
Mortgage-backed securities | Asset Pledged as Collateral without Right    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Assets pledged under repurchase agreements 1,939 1,893
Repurchase Agreements [Member]    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Secured Borrowings, Gross, Difference, Amount [1] 209 194
Corporate and asset-backed securities | Asset Pledged as Collateral without Right    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Assets pledged under repurchase agreements 22 0
Maturity Less than 30 Days [Member] | Asset Pledged as Collateral without Right    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Assets pledged under repurchase agreements 2,459 2,476
Maturity Less than 30 Days [Member] | Cash [Member] | Asset Pledged as Collateral without Right    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Assets pledged under repurchase agreements 0 0
Maturity Less than 30 Days [Member] | Non-US [Member] | Asset Pledged as Collateral without Right    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Assets pledged under repurchase agreements 1,429 1,496
Maturity Less than 30 Days [Member] | U.S. and local government securities | Asset Pledged as Collateral without Right    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Assets pledged under repurchase agreements 41 0
Maturity Less than 30 Days [Member] | Mortgage-backed securities | Asset Pledged as Collateral without Right    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Assets pledged under repurchase agreements 967 980
Maturity Less than 30 Days [Member] | Corporate and asset-backed securities | Asset Pledged as Collateral without Right    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Assets pledged under repurchase agreements 22 0
Maturity 30 to 90 Days [Member] | Asset Pledged as Collateral without Right    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Assets pledged under repurchase agreements 975 1,033
Maturity 30 to 90 Days [Member] | Cash [Member] | Asset Pledged as Collateral without Right    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Assets pledged under repurchase agreements 3 0
Maturity 30 to 90 Days [Member] | Non-US [Member] | Asset Pledged as Collateral without Right    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Assets pledged under repurchase agreements 0 0
Maturity 30 to 90 Days [Member] | U.S. and local government securities | Asset Pledged as Collateral without Right    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Assets pledged under repurchase agreements 0 129
Maturity 30 to 90 Days [Member] | Mortgage-backed securities | Asset Pledged as Collateral without Right    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Assets pledged under repurchase agreements 972 904
Maturity 30 to 90 Days [Member] | Corporate and asset-backed securities | Asset Pledged as Collateral without Right    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Assets pledged under repurchase agreements $ 0 0
Maturity Greater than 90 Days [Member] | Asset Pledged as Collateral without Right    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Assets pledged under repurchase agreements   9
Maturity Greater than 90 Days [Member] | Cash [Member] | Asset Pledged as Collateral without Right    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Assets pledged under repurchase agreements   0
Maturity Greater than 90 Days [Member] | Non-US [Member] | Asset Pledged as Collateral without Right    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Assets pledged under repurchase agreements   0
Maturity Greater than 90 Days [Member] | U.S. and local government securities | Asset Pledged as Collateral without Right    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Assets pledged under repurchase agreements   0
Maturity Greater than 90 Days [Member] | Mortgage-backed securities | Asset Pledged as Collateral without Right    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Assets pledged under repurchase agreements   9
Maturity Greater than 90 Days [Member] | Corporate and asset-backed securities | Asset Pledged as Collateral without Right    
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]    
Assets pledged under repurchase agreements   $ 0
[1] Per the repurchase agreements, the amount of collateral posted is required to exceed the amount of gross liability