Segment Information (Reconciliation Of Revenue From Segments To Consolidated) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total revenues	$ 3,255	$ 3,525	$ 3,307	$ 3,243	$ 3,171	$ 3,716	$ 3,381	$ 3,304	$ 13,330	$ 13,572	$ 13,554
Annuities Segment [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total revenues									4,033	4,120	3,746
Retirement Plan Services Segment [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total revenues									1,103	1,101	1,090
Life Insurance Segment [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total revenues									6,246	5,948	6,003
Group Protection Segment [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total revenues									2,130	2,357	2,445
Other Operations [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total revenues									332	374	432
Excluded realized gain (loss) pre-tax [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total revenues									(518)	(329)	(165)
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									3	3	3
Amortization Of DFEL Associated With Benefit Ratio Unlocking, Pre-Tax [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total revenues									1	(2)
Parent Company [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total revenues									$ 1,161	$ 1,311	$ 918