v3.25.3
Fair Value Measurements - Separate Accounts (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2025
Sep. 30, 2024
Dec. 31, 2024
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Separate account assets $ 7,533   $ 7,533   $ 7,278
Separate Account Assets          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Separate accounts assets classified in Level 3, period increase (decrease), including transfers in and out of Level 3  
Pension Plans | Separate Account, Non-Guaranteed Separate Accounts          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Separate account assets 3,800   3,800   3,800
Total          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Separate account assets 6,877   6,877   6,646
Total | Separate Account, Guaranteed Separate Accounts          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Separate account assets 581   581   576
Total | Separate Account, Non-Guaranteed Separate Accounts          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Separate account assets 6,296   6,296   6,070
Quoted Prices in Active Markets for Identical Assets (Level 1)          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Separate account assets 522   522   498
Quoted Prices in Active Markets for Identical Assets (Level 1) | Separate Account, Guaranteed Separate Accounts          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Separate account assets 248   248   231
Quoted Prices in Active Markets for Identical Assets (Level 1) | Separate Account, Non-Guaranteed Separate Accounts          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Separate account assets 274   274   267
Significant Other Observable Inputs (Level 2)          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Separate account assets 6,142   6,142   5,920
Significant Other Observable Inputs (Level 2) | Separate Account, Guaranteed Separate Accounts          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Separate account assets 333   333   345
Significant Other Observable Inputs (Level 2) | Separate Account, Non-Guaranteed Separate Accounts          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Separate account assets 5,809   5,809   5,575
Significant Unobservable Inputs (Level 3)          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Separate account assets 213   213   228
Significant Unobservable Inputs (Level 3) | Separate Account, Guaranteed Separate Accounts          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Separate account assets 0   0   0
Significant Unobservable Inputs (Level 3) | Separate Account, Non-Guaranteed Separate Accounts          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Separate account assets 213   213   228
Significant Unobservable Inputs (Level 3) | Pension Plans | Separate Account, Non-Guaranteed Separate Accounts          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Separate account assets 200   200   200
NAV          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Separate account assets $ 656   $ 656   $ 632