v3.25.2
FAIR VALUE - Schedule of Fair Value Measurement Levels for all Assets, Recorded at Fair Value (Details) - USD ($)
$ in Millions
Jun. 30, 2025
Dec. 31, 2024
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value $ 19,796 $ 17,186
Equity securities, fair value 112 110
Other invested assets, fair value 1,618 1,523
Quoted Prices in Active Markets for Identical Assets (Level 1)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 0 0
Equity securities, fair value 83 79
Other invested assets, fair value 0 0
Significant Other Observable Inputs (Level 2)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 17,484 14,997
Equity securities, fair value 25 26
Other invested assets, fair value 0 0
Significant Unobservable Inputs (Level 3)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 2,312 2,189
Equity securities, fair value 5 5
Other invested assets, fair value 1,618 1,523
U.S. Treasury securities and obligations of U.S. government agencies and corporations    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 249 255
U.S. Treasury securities and obligations of U.S. government agencies and corporations | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 0 0
U.S. Treasury securities and obligations of U.S. government agencies and corporations | Significant Other Observable Inputs (Level 2)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 249 255
U.S. Treasury securities and obligations of U.S. government agencies and corporations | Significant Unobservable Inputs (Level 3)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 0 0
Obligations of U.S. States and political subdivisions    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 50 70
Obligations of U.S. States and political subdivisions | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 0 0
Obligations of U.S. States and political subdivisions | Significant Other Observable Inputs (Level 2)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 50 70
Obligations of U.S. States and political subdivisions | Significant Unobservable Inputs (Level 3)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 0 0
Corporate securities    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 5,896 3,997
Corporate securities | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 0 0
Corporate securities | Significant Other Observable Inputs (Level 2)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 5,460 3,479
Corporate securities | Significant Unobservable Inputs (Level 3)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 436 518
Asset-backed securities    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 4,749 5,311
Asset-backed securities | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 0 0
Asset-backed securities | Significant Other Observable Inputs (Level 2)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 2,887 3,654
Asset-backed securities | Significant Unobservable Inputs (Level 3)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 1,862 1,657
Agency commercial    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 210  
Agency commercial | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 0  
Agency commercial | Significant Other Observable Inputs (Level 2)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 210  
Agency commercial | Significant Unobservable Inputs (Level 3)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 0  
Non-agency commercial    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 447  
Non-agency commercial | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 0  
Non-agency commercial | Significant Other Observable Inputs (Level 2)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 447  
Non-agency commercial | Significant Unobservable Inputs (Level 3)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 0  
Commercial    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value   441
Commercial | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value   0
Commercial | Significant Other Observable Inputs (Level 2)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value   441
Commercial | Significant Unobservable Inputs (Level 3)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value   0
Agency residential    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 3,708 3,151
Agency residential | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 0 0
Agency residential | Significant Other Observable Inputs (Level 2)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 3,708 3,151
Agency residential | Significant Unobservable Inputs (Level 3)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 0 0
Non-agency residential    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 1,374 1,161
Non-agency residential | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 0 0
Non-agency residential | Significant Other Observable Inputs (Level 2)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 1,374 1,161
Non-agency residential | Significant Unobservable Inputs (Level 3)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 0 0
Foreign government securities    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 992 970
Foreign government securities | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 0 0
Foreign government securities | Significant Other Observable Inputs (Level 2)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 992 970
Foreign government securities | Significant Unobservable Inputs (Level 3)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 0 0
Foreign corporate securities    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 2,121 1,831
Foreign corporate securities | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 0 0
Foreign corporate securities | Significant Other Observable Inputs (Level 2)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 2,107 1,817
Foreign corporate securities | Significant Unobservable Inputs (Level 3)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value $ 14 $ 14