Investments (Maturities of Fixed Maturity Securities) (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Investments, Debt and Equity Securities [Abstract]
Amortized cost, due in one year or less	$ 4,532
Amortized cost, due after one year through five years	19,189
Amortized cost, due after five years through ten years	12,818
Amortized cost, due after ten years	27,911
Amortized cost, Structured Securities	21,034
Fixed maturity securities, amortized cost	85,484	$ 86,565
Estimated fair value, due in one year or less	4,505
Estimated fair value, due after one year through five years	18,945
Estimated fair value, due after five years through ten years	12,377
Estimated fair value, due after ten years	24,480
Estimated fair value, Structured Securities	20,234
Fixed maturity securities, estimated fair value	$ 80,541	$ 79,129