v3.26.1
Investments (Amortized Cost and Fair Value of Available-for-Sale Debt Securities by Contractual Maturity) (Details) - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Schedule of Investments [Line Items]    
Due in one year or less, Amortized Cost $ 3,334  
Due after one year through five years, Amortized Cost 14,106  
Due after five years through ten years, Amortized Cost 12,664  
Due after ten years, Amortized Cost 7,685  
Total debt securities - available-for-sale, Amortized Cost 51,867 $ 49,578
Due in one year or less, Fair Value 3,316  
Due after one year through five years, Fair Value 13,770  
Due after five years through ten years, Fair Value 12,254  
Due after ten years, Fair Value 7,414  
Debt Securities, Available-for-sale 50,106 48,182
Debt Securities, Held-to-Maturity, Amortized Cost, Maturity, Allocated and Single Maturity Date, Year One 267  
Debt Securities, Held-to-Maturity, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year One Through Five 186  
Debt Securities, Held-to-Maturity, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 4  
Debt Securities, Held-to-Maturity, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 10 17  
Debt Securities, Held-to-maturity 474 490
Held-to-maturity Securities, Debt Maturities, within One Year, Fair Value 268  
Debt Securities, Held-to-Maturity, Fair Value, Maturity, Allocated and Single Maturity Date, after Year One Through Five 185  
Debt Securities, Held-to-Maturity, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 4  
Debt Securities, Held-to-Maturity, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 10 14  
Debt Securities, Held-to-maturity, Fair Value 471 489
U.S. Agency Mortgage-Backed Securities [Member]    
Schedule of Investments [Line Items]    
Mortgage-backed securities, Amortized Cost 10,901  
Total debt securities - available-for-sale, Amortized Cost 10,901 10,284
Mortgage-backed securities, Fair Value 10,275  
Debt Securities, Available-for-sale 10,275 9,719
Non-U.S. Agency Mortgage-Backed Securities [Member]    
Schedule of Investments [Line Items]    
Mortgage-backed securities, Amortized Cost 3,177  
Total debt securities - available-for-sale, Amortized Cost 3,177 2,748
Mortgage-backed securities, Fair Value 3,077  
Debt Securities, Available-for-sale $ 3,077 $ 2,660