Reinsurance - Effects of Reinsurance (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Premiums
Total premiums	$ 42,627	$ 39,714	$ 36,113
Reinsurance recoveries
Reinsurance recoveries	431	395	452
Individual life insurance and annuity business sold
Reinsurance recoveries
Reinsurance recoveries	240	238	249
Other
Reinsurance recoveries
Reinsurance recoveries	191	157	203
Short-duration contracts
Premiums
Direct	38,425	35,690	32,148
Assumed	85	64	77
Ceded	(230)	(203)	(182)
Total premiums	38,280	35,551	32,043
Long-duration contracts
Premiums
Direct	4,517	4,352	4,268
Assumed	99	105	116
Total premiums	4,347	4,163	4,070
Long-duration contracts | Individual life insurance and annuity business sold
Premiums
Ceded	(119)	(126)	(133)
Long-duration contracts | Other
Premiums
Ceded	$ (150)	$ (168)	$ (181)