Fair Value Measurements (Details 7) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Fair Value, Option, Quantitative Disclosures [Line Items]
Document Period End Date	Mar. 31, 2013
Changes in fair value of assets and liabilities accounted for using the fair value option	$ (48)	$ (41)
Corporate [Member] | Fixed Maturities, FVO [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Changes in fair value of assets and liabilities accounted for using the fair value option	(9)	1
Commercial Real Estate collateralized debt obligation [Member] | Fixed Maturities, FVO [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Changes in fair value of assets and liabilities accounted for using the fair value option	9	19
Foreign Government Debt Securities [Member] | Fixed Maturities, FVO [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Changes in fair value of assets and liabilities accounted for using the fair value option	(48)	(49)
Credit Linked Notes [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Changes in fair value of assets and liabilities accounted for using the fair value option	$ 0	$ (12)