Guaranteed Benefit Features (Information On Guaranteed Death Benefit Features) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2013		Dec. 31, 2012
Return of Net Deposits [Member]
Net Amount at Risk by Product and Guarantee [Line Items]
Total Account Value	$ 67,661		$ 63,478
Net amount at risk	251	[1]	392	[1]
Average attained age of contract holders	60 years		60 years
Minimum Return [Member]
Net Amount at Risk by Product and Guarantee [Line Items]
Total Account Value	150		149
Net amount at risk	32	[1]	37	[1]
Average attained age of contract holders	73 years		73 years
Guaranteed minimum return	5.00%		5.00%
Anniversary Contract Value [Member]
Net Amount at Risk by Product and Guarantee [Line Items]
Total Account Value	23,868		23,019
Net amount at risk	$ 795	[1]	$ 1,133	[1]
Average attained age of contract holders	68 years		67 years

[1] Represents the amount of death benefit in excess of the account balance.  The decrease in net amount at risk when comparing March 31, 2013, to December 31, 2012, was attributable primarily to the increase in the equity markets during the first three months of 2013.