Guaranteed Benefit Features (Information On Guaranteed Death Benefit Features) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014
Return of Net Deposits [Member]
Net Amount at Risk by Product and Guarantee [Line Items]
Total Account Value	[1]	$ 85,345	$ 85,917
Net Amount At Risk	[1],[2]	$ 1,201	$ 183
Average attained age of contract holders	[1]	63 years	62 years
Minimum Return [Member]
Net Amount at Risk by Product and Guarantee [Line Items]
Total Account Value	[1]	$ 111	$ 135
Net Amount At Risk	[1],[2]	$ 24	$ 25
Average attained age of contract holders	[1]	75 years	74 years
Guaranteed minimum return	[1]	5.00%	5.00%
Anniversary Contract Value [Member]
Net Amount at Risk by Product and Guarantee [Line Items]
Total Account Value	[1]	$ 24,659	$ 26,021
Net Amount At Risk	[1],[2]	$ 1,345	$ 597
Average attained age of contract holders	[1]	69 years	68 years

[1] Our variable contracts with guarantees may offer more than one type of guarantee in each contract; therefore, the amounts listed are not mutually exclusive.

[2] Represents the amount of death benefit in excess of the account balance that is subject to market fluctuations.