Investments (Maturities of Fixed Maturity Securities) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Available-for-sale Securities, Debt Maturities [Abstract]
Amortized Cost, Due in one year or less	$ 8,678
Amortized Cost, Due after one year through five years	25,467
Amortized Cost, Due after five years through ten years	26,963
Amortized Cost, Due after ten years	57,426
Amortized Cost, Structured Securities	43,596
Amortized Cost net of ACL	162,130
Estimated Fair Value, Due in one year or less	8,651
Estimated Fair Value, Due after one year through five years	26,348
Estimated Fair Value, Due after five years through ten years	30,349
Estimated Fair Value, Due after ten years	73,638
Estimated Fair Value, Structured Securities	45,588
Estimated Fair Value of Fixed Maturity Securities AFS	$ 184,574	$ 169,564