v3.26.1
Investments (Securities in a gross unrealized loss position by ratings) (Details) - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Debt Securities, Available-for-sale [Line Items]    
Estimated Fair Value $ 24,701 $ 20,644
Gross Unrealized Losses 2,568 2,286
U.S. Government, Government agencies and Government-sponsored enterprises    
Debt Securities, Available-for-sale [Line Items]    
Estimated Fair Value 2,053 1,980
Gross Unrealized Losses 271 267
AAA    
Debt Securities, Available-for-sale [Line Items]    
Estimated Fair Value 1,521 1,376
Gross Unrealized Losses 256 243
AA    
Debt Securities, Available-for-sale [Line Items]    
Estimated Fair Value 4,256 3,827
Gross Unrealized Losses 678 623
A    
Debt Securities, Available-for-sale [Line Items]    
Estimated Fair Value 6,408 5,025
Gross Unrealized Losses 513 440
BBB    
Debt Securities, Available-for-sale [Line Items]    
Estimated Fair Value 9,446 7,758
Gross Unrealized Losses 749 639
Non-investment grade    
Debt Securities, Available-for-sale [Line Items]    
Estimated Fair Value 1,017 678
Gross Unrealized Losses $ 101 $ 74