Segment Information (Reconciliation Of Revenue From Segments To Consolidated) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total revenues	$ 3,500	$ 3,243
Annuities Segment [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total revenues	1,061	1,039
Retirement Plan Services Segment [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total revenues	282	267
Life Insurance Segment [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total revenues	1,606	1,478
Group Protection Segment [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total revenues	541	534
Other Operations [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total revenues	88	82
Excluded realized gain (loss) pre-tax [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total revenues	(80)	(158)
Amortization of deferred gain arising from reserve changes on business sold through reinsurance, pre-tax [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total revenues	1	$ 1
Amortization Of DFEL Associated With Benefit Ratio Unlocking, Pre-Tax [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total revenues	$ 1