Certain Long-Duration Contracts with Guarantees (Variable Annuity, Variable Life, Variable Universal Life and Universal Life Contracts) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Annuity Contracts | Return of net deposits | In the Event of Death
Net Amount at Risk by Product and Guarantee [Line Items]
Account value	$ 130,893	$ 115,988
Net amount at risk	$ 244	$ 922
Average attained age of contractholders	67 years	66 years
Annuity Contracts | Return of net deposits | At Annuitization / Accumulation
Net Amount at Risk by Product and Guarantee [Line Items]
Account value	$ 16	$ 21
Net amount at risk	$ 0	$ 0
Average attained age of contractholders	75 years	72 years
Annuity Contracts | Minimum return or contract value | In the Event of Death
Net Amount at Risk by Product and Guarantee [Line Items]
Account value	$ 32,609	$ 30,631
Net amount at risk	$ 2,626	$ 5,066
Average attained age of contractholders	69 years	68 years
Annuity Contracts | Minimum return or contract value | At Annuitization / Accumulation
Net Amount at Risk by Product and Guarantee [Line Items]
Account value	$ 147,511	$ 131,261
Net amount at risk	$ 4,578	$ 8,235
Average attained age of contractholders	68 years	67 years
Average period remaining until earliest expected annuitization	2 months 2 days	1 month 6 days
Variable Life, Variable Universal Life and Universal Life Contracts | In the Event of Death
Net Amount at Risk by Product and Guarantee [Line Items]
Separate account value	$ 9,983	$ 8,752
General account value	18,225	16,903
Net amount at risk	$ 245,929	$ 246,644
Average attained age of contractholders	55 years	55 years