v3.25.4
Investments (Fair Value of Available-For-Sale Investments with Gross Unrealized Losses by Investment Type and Length of Time That Individual Securities Have Been in a Continuous Unrealized Loss Position) (Details) - USD ($)
$ in Millions
Dec. 31, 2025
Dec. 31, 2024
Debt Securities - available-for-sale    
Schedule of Investments [Line Items]    
Less Than 12 Months, Fair Value $ 4,214 $ 16,677
Less Than 12 Months, Gross Unrealized Losses (30) (518)
Greater Than 12 Months, Fair Value 25,100 24,223
Greater Than 12 Months, Gross Unrealized Losses (1,595) (2,440)
Total, Fair Value 29,314 40,900
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss (1,625) (2,958)
U.S. Government and Agency Obligations [Member]    
Schedule of Investments [Line Items]    
Less Than 12 Months, Fair Value 500 1,475
Less Than 12 Months, Gross Unrealized Losses (4) (51)
Greater Than 12 Months, Fair Value 2,339 2,152
Greater Than 12 Months, Gross Unrealized Losses (152) (223)
Total, Fair Value 2,839 3,627
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss (156) (274)
State and Municipal Obligations [Member]    
Schedule of Investments [Line Items]    
Less Than 12 Months, Fair Value 523 2,593
Less Than 12 Months, Gross Unrealized Losses (8) (58)
Greater Than 12 Months, Fair Value 4,342 4,085
Greater Than 12 Months, Gross Unrealized Losses (224) (317)
Total, Fair Value 4,865 6,678
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss (232) (375)
Corporate Obligations [Member]    
Schedule of Investments [Line Items]    
Less Than 12 Months, Fair Value 2,661 7,402
Less Than 12 Months, Gross Unrealized Losses (16) (213)
Greater Than 12 Months, Fair Value 10,399 11,449
Greater Than 12 Months, Gross Unrealized Losses (524) (927)
Total, Fair Value 13,060 18,851
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss (540) (1,140)
U.S. Agency Mortgage-Backed Securities [Member]    
Schedule of Investments [Line Items]    
Less Than 12 Months, Fair Value 346 4,791
Less Than 12 Months, Gross Unrealized Losses (1) (191)
Greater Than 12 Months, Fair Value 6,665 4,674
Greater Than 12 Months, Gross Unrealized Losses (597) (803)
Total, Fair Value 7,011 9,465
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss (598) (994)
Non-U.S. Agency Mortgage-Backed Securities [Member]    
Schedule of Investments [Line Items]    
Less Than 12 Months, Fair Value 184 416
Less Than 12 Months, Gross Unrealized Losses (1) (5)
Greater Than 12 Months, Fair Value 1,355 1,863
Greater Than 12 Months, Gross Unrealized Losses (98) (170)
Total, Fair Value 1,539 2,279
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss $ (99) $ (175)