Investments (Maturities of Fixed Maturity Securities) (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]
Amortized cost, due in one year or less	$ 3,210
Amortized cost, due after one year through five years	17,705
Amortized cost, due after five years through ten years	14,477
Amortized cost, due after ten years	29,444
Amortized cost, Structured Securities	21,739
Fixed maturity securities, amortized cost	86,575	$ 86,129
Estimated fair value, due in one year or less	3,165
Estimated fair value, due after one year through five years	17,122
Estimated fair value, due after five years through ten years	13,129
Estimated fair value, due after ten years	25,938
Estimated fair value, Structured Securities	20,248
Fixed maturity securities, estimated fair value	$ 79,602	$ 80,085