Reinsurance (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Guaranteed Minimum Benefits [Line Items]
Reinsurance recoveries on incurred losses and loss expenses	$ 3,300,000,000	$ 3,300,000,000	$ 3,700,000,000
Provision for uncollectible reinsurance	479,000,000	530,000,000
Guaranteed Minimum Death Benefits [Member]
Guaranteed Minimum Benefits [Line Items]
Reported liabilities	138,000,000	185,000,000
Net amount at risk	1,800,000,000	1,800,000,000
Discounting assumption used in the calculation of the benefit reserve aging - lower range	1.50%
Discounting assumption used in the calculation of the benefit reserve aging - upper range	2.50%
Percent of Annuity 2000 mortality table used for mortality assumption	100.00%
Total claim amount payable, if all of the Company's cedants' policyholders covered were to die immediately	400,000,000
Guaranteed Living Benefits [Member]
Guaranteed Minimum Benefits [Line Items]
Reported liabilities	1,500,000,000	648,000,000
Fair value derivative adjustment in liability	1,300,000,000	507,000,000
Net amount at risk	380,000,000	30,000,000
Discounting assumption used in the calculation of the benefit reserve aging - lower range	3.00%
Discounting assumption used in the calculation of the benefit reserve aging - upper range	4.00%
Percent of Annuity 2000 mortality table used for mortality assumption	100.00%
Total claim amount payable, if all of the Company's cedants' policyholders covered were to die immediately	1,100,000,000
Average attained age of all policyholders under all benefits reinsured, years	67
Guaranteed Minimum Deaths Benefits And Guaranteed Living Benefits [Member]
Guaranteed Minimum Benefits [Line Items]
GMBD net amount of risk	182,000,000	145,000,000
GLB net amount of risk	998,000,000	619,000,000
Discounting assumption used in the calculation of the benefit reserve aging - lower range	1.00%
Discounting assumption used in the calculation of the benefit reserve aging - upper range	2.00%
Percent of Annuity 2000 mortality table used for mortality assumption	100.00%
GLB policyholders claims	$ 0