Segment Information (Reconciliation Of Income (Loss) From Operations By Segment To Consolidated Net Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Reconciliation of Net Income (Loss) from Segments to Consolidated [Abstract]
Net income (loss)	$ 52	$ 252
Segment Reconciling Items [Member]
Reconciliation of Net Income (Loss) from Segments to Consolidated [Abstract]
Excluded realized gain (loss), after-tax	(60)	(316)
Benefit ratio unlocking, after-tax	(349)	142
Acquisition and integration costs related to mergers and acquisitions, after tax	(4)	(15)
Annuities Segment [Member]
Reconciliation of Net Income (Loss) from Segments to Consolidated [Abstract]
Net income (loss)	261	250
Retirement Plan Services Segment [Member]
Reconciliation of Net Income (Loss) from Segments to Consolidated [Abstract]
Net income (loss)	40	39
Life Insurance Segment [Member]
Reconciliation of Net Income (Loss) from Segments to Consolidated [Abstract]
Net income (loss)	171	157
Group Protection Segment [Member]
Reconciliation of Net Income (Loss) from Segments to Consolidated [Abstract]
Net income (loss)	40	55
Other Operations [Member]
Reconciliation of Net Income (Loss) from Segments to Consolidated [Abstract]
Net income (loss)	$ (47)	$ (60)