Reinsurance - Effect of Reinsurance (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Premiums:
Direct premiums	$ 2,759	$ 2,602	$ 2,597
Reinsurance assumed	827	956	1,152
Reinsurance ceded	(1,313)	(1,426)	(1,652)
Net premiums	2,273	2,132	2,097
Fee income:
Gross fee income	1,970	1,983	1,890
Reinsurance ceded	(1)	(1)	(1)
Net fee income	1,969	1,982	1,889
Policyholder Benefits and Claims Incurred, Assumed and Ceded [Abstract]
Direct interest credited and other benefits to contract owners / policyholders	4,186	3,912	4,090
Reinsurance assumed	9	554	23
Reinsurance ceded	(445)	(940)	(455)
Net interest credited and other benefits to contract owners / policyholders	3,750	3,526	3,658
UL contracts
Policyholder Benefits and Claims Incurred, Assumed and Ceded [Abstract]
Reinsurance ceded	$ (232)	$ (216)	$ (219)