Guaranteed Benefit Features (Information On Guaranteed Death Benefit Features) (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
		Mar. 31, 2016	Dec. 31, 2015
Return of Net Deposits [Member]
Net Amount at Risk by Product and Guarantee [Line Items]
Total Account Value	[1]	$ 85,270	$ 85,345
Net Amount At Risk	[1],[2]	$ 1,269	$ 1,201
Average attained age of contract holders	[1]	63 years	63 years
Minimum Return [Member]
Net Amount at Risk by Product and Guarantee [Line Items]
Total Account Value	[1]	$ 106	$ 111
Net Amount At Risk	[1],[2]	$ 24	$ 24
Average attained age of contract holders	[1]	75 years	75 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]	$ 24,397	$ 24,659
Net Amount At Risk	[1],[2]	$ 1,359	$ 1,345
Average attained age of contract holders	[1]	69 years	69 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.