v3.25.3
Investments - Available-for-Sale Investments (Details)
$ in Millions
Sep. 30, 2025
USD ($)
position
Dec. 31, 2024
USD ($)
position
Debt Securities, Available-for-sale [Line Items]    
In a Continuous Loss Position for Less than 12 Months, Estimated Fair Value $ 92 $ 1,204
In a Continuous Loss Position for Less than 12 Months, Gross Unrealized Losses $ 1 $ 17
In a Continuous Loss Position for Less than 12 Months, Total Number of Positions | position 65 813
In a Continuous Loss Position for 12 Months or More, Estimated Fair Value $ 995 $ 1,594
In a Continuous Loss Position for 12 Months or More, Gross Unrealized Losses $ 38 $ 72
In a Continuous Loss Position for 12 Months or More, Total Number of Positions | position 583 871
Corporate debt securities    
Debt Securities, Available-for-sale [Line Items]    
In a Continuous Loss Position for Less than 12 Months, Estimated Fair Value $ 0 $ 811
In a Continuous Loss Position for Less than 12 Months, Gross Unrealized Losses $ 0 $ 10
In a Continuous Loss Position for Less than 12 Months, Total Number of Positions | position 0 541
In a Continuous Loss Position for 12 Months or More, Estimated Fair Value $ 493 $ 935
In a Continuous Loss Position for 12 Months or More, Gross Unrealized Losses $ 9 $ 25
In a Continuous Loss Position for 12 Months or More, Total Number of Positions | position 243 449
Mortgage-backed securities    
Debt Securities, Available-for-sale [Line Items]    
In a Continuous Loss Position for Less than 12 Months, Estimated Fair Value $ 92 $ 271
In a Continuous Loss Position for Less than 12 Months, Gross Unrealized Losses $ 1 $ 5
In a Continuous Loss Position for Less than 12 Months, Total Number of Positions | position 65 197
In a Continuous Loss Position for 12 Months or More, Estimated Fair Value $ 339 $ 406
In a Continuous Loss Position for 12 Months or More, Gross Unrealized Losses $ 23 $ 36
In a Continuous Loss Position for 12 Months or More, Total Number of Positions | position 212 244
Asset-backed securities    
Debt Securities, Available-for-sale [Line Items]    
In a Continuous Loss Position for Less than 12 Months, Estimated Fair Value $ 0 $ 84
In a Continuous Loss Position for Less than 12 Months, Gross Unrealized Losses $ 0 $ 1
In a Continuous Loss Position for Less than 12 Months, Total Number of Positions | position 0 48
In a Continuous Loss Position for 12 Months or More, Estimated Fair Value $ 87 $ 143
In a Continuous Loss Position for 12 Months or More, Gross Unrealized Losses $ 3 $ 5
In a Continuous Loss Position for 12 Months or More, Total Number of Positions | position 44 73
Municipal securities    
Debt Securities, Available-for-sale [Line Items]    
In a Continuous Loss Position for Less than 12 Months, Estimated Fair Value $ 0 $ 38
In a Continuous Loss Position for Less than 12 Months, Gross Unrealized Losses $ 0 $ 1
In a Continuous Loss Position for Less than 12 Months, Total Number of Positions | position 0 27
In a Continuous Loss Position for 12 Months or More, Estimated Fair Value $ 62 $ 95
In a Continuous Loss Position for 12 Months or More, Gross Unrealized Losses $ 2 $ 4
In a Continuous Loss Position for 12 Months or More, Total Number of Positions | position 67 89
Other    
Debt Securities, Available-for-sale [Line Items]    
In a Continuous Loss Position for Less than 12 Months, Estimated Fair Value $ 0 $ 0
In a Continuous Loss Position for Less than 12 Months, Gross Unrealized Losses $ 0 $ 0
In a Continuous Loss Position for Less than 12 Months, Total Number of Positions | position 0 0
In a Continuous Loss Position for 12 Months or More, Estimated Fair Value $ 14 $ 15
In a Continuous Loss Position for 12 Months or More, Gross Unrealized Losses $ 1 $ 2
In a Continuous Loss Position for 12 Months or More, Total Number of Positions | position 17 16