Segment Information (Reconciliation Of Revenue From Segments To Consolidated) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total revenues	$ 3,171	$ 3,716	$ 3,381	$ 3,304	$ 3,685	$ 3,411	$ 3,282	$ 3,176	$ 13,572	$ 13,554	$ 11,969
Annuities Segment [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total revenues									4,120	3,746	3,321
Retirement Plan Services Segment [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total revenues									1,101	1,090	1,071
Life Segment [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total revenues									5,948	6,003	5,170
Group Protection Segment [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total revenues									2,357	2,445	2,260
Other Operations [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total revenues									374	432	417
Excluded realized gain (loss) pre-tax [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total revenues									(329)	(165)	(274)
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									(2)		1
Parent Company [Member]
Schedule Of Segment Reporting And Reconcilliation [Line Items]
Total revenues									$ 1,311	$ 918	$ 849