Segment Information (Reconciliation Of Revenue From Segments To Consolidated) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Segment Reporting Information [Line Items]
Total revenues	$ 3,577	$ 3,307	$ 7,077	$ 6,551
Annuities Segment [Member]
Segment Reporting Information [Line Items]
Total revenues	1,076	983	2,138	2,022
Retirement Plan Services Segment [Member]
Segment Reporting Information [Line Items]
Total revenues	290	270	571	537
Life Insurance Segment [Member]
Segment Reporting Information [Line Items]
Total revenues	1,655	1,538	3,260	3,016
Group Protection Segment [Member]
Segment Reporting Information [Line Items]
Total revenues	541	525	1,082	1,059
Other Operations [Member]
Segment Reporting Information [Line Items]
Total revenues	67	79	155	161
Excluded realized gain (loss) pre-tax [Member]
Segment Reporting Information [Line Items]
Total revenues	$ (52)	(89)	(132)	(245)
Amortization of deferred gain arising from reserve changes on business sold through reinsurance, pre-tax [Member]
Segment Reporting Information [Line Items]
Total revenues		$ 1	1	$ 1
Amortization Of DFEL Associated With Benefit Ratio Unlocking, Pre-Tax [Member]
Segment Reporting Information [Line Items]
Total revenues			$ 2