v3.26.1
Fair Value - Summary of Quantitative Information about Level 3 Fair Value Measurements (Details) - USD ($)
$ in Millions
3 Months Ended 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2025
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Investments, fair value $ 94,131 $ 83,664 $ 97,373
Fair Value, Inputs, Level 3      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Investments, fair value 95 105 105
Fair Value, Inputs, Level 3 | Total Quantitative Level Three Securities      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Investments, fair value 58 74 69
Fair Value, Inputs, Level 3 | Third Party Pricing Exemption Securities      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Investments, fair value 37 31 36
Fair Value, Inputs, Level 3 | Corporate and other debt | Total Quantitative Level Three Securities      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Investments, fair value $ 4 $ 5 $ 4
Fair value inputs, market cap price change percentage, range, minimum   0.70% (0.10%)
Fair value inputs, market cap price change percentage, range, maximum (1.00%) 0.80% 0.10%
Fair value inputs, market cap price change percentage, weighted average (1.00%) 0.80% 0.00%
Fair Value, Inputs, Level 3 | Nonredeemable preferred stocks | Total Quantitative Level Three Securities      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Investments, fair value $ 49 $ 60 $ 60
Fair value inputs, market cap price change percentage, range, minimum (23.60%) (11.80%) (14.50%)
Fair value inputs, market cap price change percentage, range, maximum 0.00% 16.10% 7.60%
Fair value inputs, market cap price change percentage, weighted average (12.40%) 6.40% (4.50%)
Fair Value, Inputs, Level 3 | Common equities | Total Quantitative Level Three Securities      
Fair Value Measurement Inputs and Valuation Techniques [Line Items]      
Investments, fair value $ 5 $ 9 $ 5
Fair value inputs, market cap price change percentage, range, minimum (41.30%) (36.80%) (40.90%)
Fair value inputs, market cap price change percentage, range, maximum (12.90%) 41.50% 36.30%
Fair value inputs, market cap price change percentage, weighted average (23.60%) 6.70% 7.60%