Segment Information (Reconciliation Of Revenue From Segments To Consolidated) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Total revenues	$ 4,344	$ 4,638	$ 4,310	$ 3,965	$ 4,531	$ 4,264	$ 4,020	$ 3,609	$ 17,258	$ 16,424	$ 14,257
Annuities Segment [Member]
Segment Reporting Information [Line Items]
Total revenues									4,600	4,383	4,378
Retirement Plan Services Segment [Member]
Segment Reporting Information [Line Items]
Total revenues									1,200	1,178	1,165
Life Insurance Segment [Member]
Segment Reporting Information [Line Items]
Total revenues									7,438	6,922	6,558
Group Protection Segment [Member]
Segment Reporting Information [Line Items]
Total revenues									4,588	3,757	2,201
Other Operations [Member]
Segment Reporting Information [Line Items]
Total revenues									220	235	287
Excluded realized gain (loss) [Member]
Segment Reporting Information [Line Items]
Total revenues									(794)	(46)	(336)
Amortization of deferred gain arising from reserve changes on business sold through reinsurance, pre-tax [Member]
Segment Reporting Information [Line Items]
Total revenues											1
Amortization Of DFEL Associated With Benefit Ratio Unlocking, Pre-Tax [Member]
Segment Reporting Information [Line Items]
Total revenues									$ 6	$ (5)	$ 3