Investments, Available-for-sale Fixed Maturity Securities by Contractual Maturity (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Cost or Amortized Cost
Cost or amortized cost	$ 39,952	$ 38,963
Estimated Fair Value
Estimated fair value	44,380	44,646
Available-for-sale Fixed Maturities
Cost or Amortized Cost
Due in one year or less	1,603	1,456
Due after one year through five years	10,637	12,304
Due after five years through ten years	13,294	12,319
Due after ten years	14,411	12,847
Cost or amortized cost	39,945	38,926
Estimated Fair Value
Due in one year or less	1,624	1,458
Due after one year through five years	11,229	13,098
Due after five years through ten years	14,338	13,878
Due after ten years	17,182	16,170
Estimated fair value	$ 44,373	$ 44,604