Segment Information (Operating Income of Reportable Segments) (Reconciling Items) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
(Gains) Losses On Assets Supporting Experience-Rated Contractholder Liabilities, Net	$ 971	$ (863)	$ 336
Segment Reconciling Items
Segment Reporting Information [Line Items]
Terminated hedges of foreign currency earnings	65	(15)	(15)
Current period yield adjustments	331	367	434
Principal source of earnings	(37)	219	(8)
Investments carried at fair value through net income	558	(417)	184
Foreign currency exchange movements	61	(289)	(135)
Other activities	(31)	(41)	(20)
(Gains) Losses On Assets Supporting Experience-Rated Contractholder Liabilities, Net	$ 22	$ (153)	$ 185