Segment Information (Reconciliation Of Revenue From Segments To Consolidated) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Total revenues	$ 4,020	$ 3,577	$ 7,629	$ 7,077
Annuities Segment [Member]
Segment Reporting Information [Line Items]
Total revenues	1,106	1,076	2,180	2,138
Retirement Plan Services Segment [Member]
Segment Reporting Information [Line Items]
Total revenues	292	290	584	571
Life Insurance Segment [Member]
Segment Reporting Information [Line Items]
Total revenues	1,680	1,655	3,340	3,260
Group Protection Segment [Member]
Segment Reporting Information [Line Items]
Total revenues	937	541	1,490	1,082
Other Operations [Member]
Segment Reporting Information [Line Items]
Total revenues	58	67	125	155
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Excluded realized gain (loss), pre-tax	$ (53)	$ (52)	(89)	(132)
Amortization of deferred gain arising from reserve changes on business sold through reinsurance, pre-tax				1
Amortization of DFEL associated with benefit ratio unlocking, pre-tax			$ (1)	$ 2