v3.25.3
Fair Value Measurements - Financial Assets and Liabilities Carried at Fair Value (Details) - USD ($)
$ in Millions
Sep. 30, 2025
Dec. 31, 2024
Financial assets at fair value:    
Equity securities $ 134 $ 37
Recurring    
Financial assets at fair value:    
Debt Securities 8,351  
Equity securities 134 37
Short-term investments 276 170
Quoted Prices in Active Markets for Identical Assets (Level 1) | Recurring    
Financial assets at fair value:    
Debt Securities 105  
Equity securities 76 1
Short-term investments 0 0
Significant Other Observable Inputs (Level 2) | Recurring    
Financial assets at fair value:    
Debt Securities 7,895  
Equity securities 46 36
Short-term investments 276 170
Significant Unobservable Inputs (Level 3) | Recurring    
Financial assets at fair value:    
Debt Securities 351  
Equity securities 12 0
Short-term investments 0 0
Federal government and agency | Recurring    
Financial assets at fair value:    
Debt Securities 226  
Federal government and agency | Quoted Prices in Active Markets for Identical Assets (Level 1) | Recurring    
Financial assets at fair value:    
Debt Securities 105  
Federal government and agency | Significant Other Observable Inputs (Level 2) | Recurring    
Financial assets at fair value:    
Debt Securities 121  
Federal government and agency | Significant Unobservable Inputs (Level 3) | Recurring    
Financial assets at fair value:    
Debt Securities 0  
State and local government | Recurring    
Financial assets at fair value:    
Debt Securities 25  
State and local government | Quoted Prices in Active Markets for Identical Assets (Level 1) | Recurring    
Financial assets at fair value:    
Debt Securities 0  
State and local government | Significant Other Observable Inputs (Level 2) | Recurring    
Financial assets at fair value:    
Debt Securities 25  
State and local government | Significant Unobservable Inputs (Level 3) | Recurring    
Financial assets at fair value:    
Debt Securities 0  
Foreign government | Recurring    
Financial assets at fair value:    
Debt Securities 412  
Foreign government | Quoted Prices in Active Markets for Identical Assets (Level 1) | Recurring    
Financial assets at fair value:    
Debt Securities 0  
Foreign government | Significant Other Observable Inputs (Level 2) | Recurring    
Financial assets at fair value:    
Debt Securities 412  
Foreign government | Significant Unobservable Inputs (Level 3) | Recurring    
Financial assets at fair value:    
Debt Securities 0  
Corporate | Recurring    
Financial assets at fair value:    
Debt Securities 7,443  
Corporate | Quoted Prices in Active Markets for Identical Assets (Level 1) | Recurring    
Financial assets at fair value:    
Debt Securities 0  
Corporate | Significant Other Observable Inputs (Level 2) | Recurring    
Financial assets at fair value:    
Debt Securities 7,130  
Corporate | Significant Unobservable Inputs (Level 3) | Recurring    
Financial assets at fair value:    
Debt Securities 313  
Mortgage and other asset-backed | Recurring    
Financial assets at fair value:    
Debt Securities 245  
Mortgage and other asset-backed | Quoted Prices in Active Markets for Identical Assets (Level 1) | Recurring    
Financial assets at fair value:    
Debt Securities 0  
Mortgage and other asset-backed | Significant Other Observable Inputs (Level 2) | Recurring    
Financial assets at fair value:    
Debt Securities 207  
Mortgage and other asset-backed | Significant Unobservable Inputs (Level 3) | Recurring    
Financial assets at fair value:    
Debt Securities 38  
Derivatives | Recurring    
Financial assets at fair value:    
Derivative assets 1,010 168
Liabilities, Fair Value Disclosure [Abstract]    
Derivative liabilities 340 1
Derivatives | Quoted Prices in Active Markets for Identical Assets (Level 1) | Recurring    
Financial assets at fair value:    
Derivative assets 0 0
Liabilities, Fair Value Disclosure [Abstract]    
Derivative liabilities 0 0
Derivatives | Significant Other Observable Inputs (Level 2) | Recurring    
Financial assets at fair value:    
Derivative assets 74 168
Liabilities, Fair Value Disclosure [Abstract]    
Derivative liabilities 20 1
Derivatives | Significant Unobservable Inputs (Level 3) | Recurring    
Financial assets at fair value:    
Derivative assets 936 0
Liabilities, Fair Value Disclosure [Abstract]    
Derivative liabilities $ 320 $ 0