v3.24.2.u1
Insurance Contracts Financial Guarantee Insurance Contracts - Components of Loss and Loss Expense Reserves and Subrogation Recoverable (Details) - USD ($)
$ in Millions
 6 Months Ended
Jun. 30, 2024
Jun. 30, 2023
Dec. 31, 2023
Dec. 31, 2022
Components of Loss and Loss Expense Reserves and Subrogation Recoverable [Line Items]        
Ceded Loss And Loss Expenses Paid Not Yet Recovered   $ 5    
Policyholder Benefits and Claims Incurred, Ceded $ 98 45    
Subrogation recoverable (128)   $ (137)  
Claim liability reported on Balance Sheet, before reinsurance 476   559  
Liability for Claims and Claims Adjustment Expense 890   893  
Liability for Claim and Claim Adjustment Expenses Net of Subrogation recoverables 762 $ 724 756 $ 534
Property and Casualty, Commercial Insurance        
Components of Loss and Loss Expense Reserves and Subrogation Recoverable [Line Items]        
Liability for Claims and Claims Adjustment Expense 286   197  
Liability for Claim and Claim Adjustment Expenses Net of Subrogation recoverables 286   197  
Present Value of Expected Net Cash Flows- Claims and Loss Expenses [Member]        
Components of Loss and Loss Expense Reserves and Subrogation Recoverable [Line Items]        
Subrogation recoverable 7   1  
Claim liability reported on Balance Sheet, before reinsurance 676   780  
Liability for Claims and Claims Adjustment Expense 669   779  
Present Value of Expected Net Cash Flows-Recoveries [Member]        
Components of Loss and Loss Expense Reserves and Subrogation Recoverable [Line Items]        
Subrogation recoverable (136)   (139)  
Claim liability reported on Balance Sheet, before reinsurance (186)   (194)  
Liability for Claims and Claims Adjustment Expense (51)   (55)  
Unearned Premium Reserve [Member]        
Components of Loss and Loss Expense Reserves and Subrogation Recoverable [Line Items]        
Subrogation recoverable 0   0  
Claim liability reported on Balance Sheet, before reinsurance (14)   (28)  
Liability for Claims and Claims Adjustment Expense $ (14)   $ (28)