v3.26.1
Fair Value Measurements - Separate Accounts (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Dec. 31, 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Separate account assets $ 7,525   $ 7,525   $ 7,487
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          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Separate account assets         3,800
Pension Plans | Separate Account, Non-Guaranteed Separate Accounts          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Separate account assets 3,700   3,700    
Total          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Separate account assets 6,866   6,866   6,826
Total | Separate Account, Guaranteed Separate Accounts          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Separate account assets 583   583   577
Total | Separate Account, Non-Guaranteed Separate Accounts          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Separate account assets 6,283   6,283   6,249
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 516   516   518
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 252   252   247
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 264   264   271
Significant Other Observable Inputs (Level 2)          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Separate account assets 6,190   6,190   6,099
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 331   331   330
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 5,859   5,859   5,769
Significant Unobservable Inputs (Level 3)          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Separate account assets 160   160   209
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 160   160   209
Significant Unobservable Inputs (Level 3) | Pension Plans          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Separate account assets 100   100   200
NAV          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Separate account assets $ 659   $ 659   $ 661