v3.26.1
FAIR VALUE - Schedule of Fair Value Measurement Levels for all Assets and Liabilities (Details) - USD ($)
$ in Millions
Jun. 30, 2026
Dec. 31, 2025
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair value $ 34,445 $ 34,573
Equity securities, fair value 185 180
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 96 88
Significant Other Observable Inputs (Level 2)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair value 31,639 32,099
Equity securities, fair value 89 92
Significant Unobservable Inputs (Level 3)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair value 2,806 2,474
Equity securities, fair value 0 0
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 812 830
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 812 830
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
Tax-exempt obligations of U.S. states and political subdivisions    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair value 37 41
Tax-exempt 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
Tax-exempt 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 37 41
Tax-exempt 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 9,689 9,882
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 9,324 9,512
Corporate securities | Significant Unobservable Inputs (Level 3)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair value 365 370
Asset-backed securities    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair value 5,033 5,077
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 2,605 2,987
Asset-backed securities | Significant Unobservable Inputs (Level 3)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair value 2,428 2,091
Agency commercial    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair value 405 412
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 0
Agency commercial | Significant Other Observable Inputs (Level 2)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair value 405 412
Agency commercial | Significant Unobservable Inputs (Level 3)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair value 0 0
Non-agency commercial    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair value 1,198 1,121
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 0
Non-agency commercial | Significant Other Observable Inputs (Level 2)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair value 1,198 1,121
Non-agency commercial | Significant Unobservable Inputs (Level 3)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair value 0 0
Agency residential    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair value 5,138 5,465
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 5,138 5,465
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 1,771 1,721
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 1,771 1,721
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 2,226 2,371
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 2,226 2,371
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 8,136 7,653
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 8,123 7,639
Foreign corporate securities | Significant Unobservable Inputs (Level 3)    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair value $ 13 $ 14