v3.26.1
Fair Value Measurements - Financial Assets and Liabilities Carried at Fair Value (Details) - USD ($)
$ in Millions
Jun. 30, 2026
Dec. 31, 2025
Financial assets at fair value:    
Equity securities $ 106 $ 92
Recurring    
Financial assets at fair value:    
Debt Securities 8,450 8,362
Equity securities 106 92
Short-term investments 305 257
Quoted Prices in Active Markets for Identical Assets (Level 1) | Recurring    
Financial assets at fair value:    
Debt Securities 103 105
Equity securities 77 54
Short-term investments 0 0
Significant Other Observable Inputs (Level 2) | Recurring    
Financial assets at fair value:    
Debt Securities 8,051 7,932
Equity securities 27 36
Short-term investments 305 257
Significant Unobservable Inputs (Level 3) | Recurring    
Financial assets at fair value:    
Debt Securities 296 325
Equity securities 2 2
Short-term investments 0 0
Federal government and agency | Recurring    
Financial assets at fair value:    
Debt Securities 225 227
Federal government and agency | Quoted Prices in Active Markets for Identical Assets (Level 1) | Recurring    
Financial assets at fair value:    
Debt Securities 103 105
Federal government and agency | Significant Other Observable Inputs (Level 2) | Recurring    
Financial assets at fair value:    
Debt Securities 122 122
Federal government and agency | Significant Unobservable Inputs (Level 3) | Recurring    
Financial assets at fair value:    
Debt Securities 0 0
State and local government | Recurring    
Financial assets at fair value:    
Debt Securities 25 25
State and local government | Quoted Prices in Active Markets for Identical Assets (Level 1) | Recurring    
Financial assets at fair value:    
Debt Securities 0 0
State and local government | Significant Other Observable Inputs (Level 2) | Recurring    
Financial assets at fair value:    
Debt Securities 25 25
State and local government | Significant Unobservable Inputs (Level 3) | Recurring    
Financial assets at fair value:    
Debt Securities 0 0
Foreign government | Recurring    
Financial assets at fair value:    
Debt Securities 464 456
Foreign government | Quoted Prices in Active Markets for Identical Assets (Level 1) | Recurring    
Financial assets at fair value:    
Debt Securities 0 0
Foreign government | Significant Other Observable Inputs (Level 2) | Recurring    
Financial assets at fair value:    
Debt Securities 464 446
Foreign government | Significant Unobservable Inputs (Level 3) | Recurring    
Financial assets at fair value:    
Debt Securities 0 10
Corporate | Recurring    
Financial assets at fair value:    
Debt Securities 7,509 7,410
Corporate | Quoted Prices in Active Markets for Identical Assets (Level 1) | Recurring    
Financial assets at fair value:    
Debt Securities 0 0
Corporate | Significant Other Observable Inputs (Level 2) | Recurring    
Financial assets at fair value:    
Debt Securities 7,246 7,133
Corporate | Significant Unobservable Inputs (Level 3) | Recurring    
Financial assets at fair value:    
Debt Securities 263 277
Mortgage and other asset-backed | Recurring    
Financial assets at fair value:    
Debt Securities 227 244
Mortgage and other asset-backed | Quoted Prices in Active Markets for Identical Assets (Level 1) | Recurring    
Financial assets at fair value:    
Debt Securities 0 0
Mortgage and other asset-backed | Significant Other Observable Inputs (Level 2) | Recurring    
Financial assets at fair value:    
Debt Securities 194 206
Mortgage and other asset-backed | Significant Unobservable Inputs (Level 3) | Recurring    
Financial assets at fair value:    
Debt Securities 33 38
Derivatives | Recurring    
Financial assets at fair value:    
Derivative assets 1,294 991
Liabilities, Fair Value Disclosure [Abstract]    
Derivative liabilities 466 376
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 84 68
Liabilities, Fair Value Disclosure [Abstract]    
Derivative liabilities 10 22
Derivatives | Significant Unobservable Inputs (Level 3) | Recurring    
Financial assets at fair value:    
Derivative assets 1,210 923
Liabilities, Fair Value Disclosure [Abstract]    
Derivative liabilities $ 456 $ 354