Guaranteed Minimum Death Benefit Contracts (Details) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Guaranteed Minimum Death Benefits Reserve Table Details [Abstract]
Balance at January 1	$ 1,081,000,000	$ 1,170,000,000	$ 1,138,000,000
Add: Unpaid Claims	38,000,000	40,000,000	37,000,000
Less: Reinsurance and other amounts recoverable	44,000,000	53,000,000	51,000,000
Balance at January 1, net	1,075,000,000	1,157,000,000	1,124,000,000
Add: Incurred benefits	(50,000,000)	138,000,000
Less: Paid benefits	32,000,000	105,000,000
Ending balance, net	1,075,000,000	1,157,000,000	1,124,000,000
Less: Unpaid Claims	38,000,000	40,000,000	37,000,000
Add: Reinsurance and other amounts recoverable	44,000,000	53,000,000	51,000,000
Ending balance	1,081,000,000	1,170,000,000	1,138,000,000
Guaranteed Minimum Death Benefit Reserving Assumptions [Abstract]
Largest Customer Percent of Reserve	70.00%
Lapse Rate Assumption Low	0.00%	0.00%
Lapse Rate Assumption High	18.00%	24.00%
Partial Surrenders Estimate Annual Election Rate Low	0.00%	0.00%
Partial Surrenders Estimate Annual Election Rate High	13.00%	15.00%
Volatility Assumption Varying By Equity Fund Type Low	18.00%	16.00%
Volatility Assumption Varying By Equity Fund Type High	24.00%	25.00%
Volatility Assumption Varying By Bond Fund Type Low	5.00%	4.00%
Volatility Assumption Varying By Bond Fund Type High	7.00%	10.00%
Volatility Assumption Varying By Money Market Fund Type Low	0.00%	2.00%
Volatility Assumption Varying By Money Market Fund Type High	1.00%	2.00%
Guaranteed Minimum Death Benefit Contracts Text Details [Abstract]
GMDB future policy benefit reserves	1,081,000,000	1,170,000,000	1,138,000,000
Guaranteed Minimum Death Benefit Mutual Fund Investment Balance	14,500,000,000	13,800,000,000
Guaranteed Minimum Death Benefit Death Benefit Coverage In Force	4,300,000,000	5,400,000,000
Guaranteed Minimum Death Benefits Total Contractholders	470,000	480,000
Guaranteed Minimum Death Benefit Reserve Strengthening Abstract [Line Items]
Pre Tax Guaranteed Minimum Death Benefit Reserve Strengthening	18,000,000	70,000,000
After Tax Guaranteed Minimum Death Benefit Reserve Strengthening	11,000,000	45,000,000
Volatility-related impacts due to equity market conditions
Guaranteed Minimum Death Benefit Reserve Strengthening Abstract [Line Items]
Pre Tax Guaranteed Minimum Death Benefit Reserve Strengthening		34,000,000
After Tax Guaranteed Minimum Death Benefit Reserve Strengthening		22,000,000
Interest rate impacts
Guaranteed Minimum Death Benefit Reserve Strengthening Abstract [Line Items]
Pre Tax Guaranteed Minimum Death Benefit Reserve Strengthening		22,000,000
After Tax Guaranteed Minimum Death Benefit Reserve Strengthening		15,000,000
Impacts of overall market declines
Guaranteed Minimum Death Benefit Reserve Strengthening Abstract [Line Items]
Pre Tax Guaranteed Minimum Death Benefit Reserve Strengthening		13
After Tax Guaranteed Minimum Death Benefit Reserve Strengthening		$ 8