v3.25.2
Fair Value - Summary of Quantitative Information about Level 3 Fair Value Measurements (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Mar. 31, 2025
Jun. 30, 2025
Jun. 30, 2024
Dec. 31, 2024
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Investments, fair value   $ 88,610 $ 72,356 $ 80,250
Fair Value, Inputs, Level 3        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Investments, fair value   106 101 105
Fair Value, Inputs, Level 3 | Total Quantitative Level Three Securities        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Investments, fair value   74 77 80
Fair Value, Inputs, Level 3 | Third Party Pricing Exemption Securities        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Investments, fair value   32 24 25
Fair Value, Inputs, Level 3 | Corporate and other debt securities | Total Quantitative Level Three Securities        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Investments, fair value   $ 5 $ 3 5
Fair value inputs, market cap price change percentage, range, minimum (1.40%) 0.60% (1.20%)  
Fair value inputs, market cap price change percentage, range, maximum (1.30%) 0.80% 1.20%  
Fair value inputs, market cap price change percentage, weighted average (1.40%) 0.70% 0.20%  
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   $ 60 $ 52 52
Fair value inputs, market cap price change percentage, range, minimum (14.10%) (13.10%) (7.60%)  
Fair value inputs, market cap price change percentage, range, maximum 6.00% 22.70% (1.50%)  
Fair value inputs, market cap price change percentage, weighted average (2.70%) 3.70% (2.90%)  
Fair Value, Inputs, Level 3 | Common equities | Total Quantitative Level Three Securities        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Investments, fair value   $ 9 $ 22 $ 23
Fair value inputs, market cap price change percentage, range, minimum (41.30%) (26.30%) (26.50%)  
Fair value inputs, market cap price change percentage, range, maximum 95.90% 56.60% 19.30%  
Fair value inputs, market cap price change percentage, weighted average 6.00% 21.30% (4.40%)