Segment Information (Reconciliation Of Revenue From Segments To Consolidated) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting Information [Line Items]
Total revenues	$ 3,609	$ 3,500
Annuities Segment [Member]
Segment Reporting Information [Line Items]
Total revenues	1,073	1,061
Retirement Plan Services Segment [Member]
Segment Reporting Information [Line Items]
Total revenues	292	282
Life Insurance Segment [Member]
Segment Reporting Information [Line Items]
Total revenues	1,660	1,606
Group Protection Segment [Member]
Segment Reporting Information [Line Items]
Total revenues	553	541
Other Operations [Member]
Segment Reporting Information [Line Items]
Total revenues	67	88
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Excluded realized gain (loss), pre-tax	(35)	(80)
Amortization of deferred gain arising from reserve changes on business sold through reinsurance, pre-tax		1
Amortization of DFEL associated with benefit ratio unlocking	$ (1)	$ 1