Derivative Financial Instruments (Details Textuals) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Derivative Instruments, Gain (Loss) [Line Items]
Embedded derivatives	$ 91,000,000	$ 43,000,000	$ 270,000,000	$ 114,000,000
Derivative Instrument Detail [Abstract]
Net amounts reclassified into net derivatives gains (losses) on discontinued cash flow hedges	0	0	0	(1,000,000)
Hedging exposure to variability in future cash flows for specific length of time	6 years	6 years
Deferred net gains (losses) expected to be reclassified to earnings	2,000,000
Maximum Amount of Future Payments under Credit Default Swaps	2,502,000,000		2,502,000,000		2,100,000,000
Estimated Fair Value of Credit Default Swaps	19,000,000		19,000,000		(11,000,000)
Cash collateral received for collateral arrangements and obligated to return	1,300,000,000		1,300,000,000		1,600,000,000
Fair Value of Securities Received as Collateral that Can be Resold or Repledged	391,000,000		391,000,000		315,000,000
Securities Received as Collateral, Amount Repledged and Sold			0
Estimated fair value of over-the-counter derivatives with credit-contingent provisions in gross liability position	175,000,000		175,000,000
Additional Collateral Required for Derivatives in Gross Liability Position	133,000,000		133,000,000
Gross derivative asset for which the Company has the contractual right of offset	111,000,000		111,000,000
Securities owned and pledged as collateral for exchange-traded futures	0		0		0
Cash collateral owned and pledged as collateral for exchange-traded futures	98,000,000		98,000,000		140,000,000
Nonperformance Risk [Member] | Ceded Guaranteed Minimum Benefit [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Embedded derivatives	202,000,000	(542,000,000)	241,000,000	(519,000,000)
Nonperformance Risk [Member] | Direct And Assumed Guaranteed Minimum Benefit [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Embedded derivatives	(110,000,000)	419,000,000	(212,000,000)	391,000,000
Fixed maturity securities [Member]
Derivatives, Fair Value [Line Items]
Estimated fair value of securities collateral provided for over-the-counter derivatives with credit-contingent provisions in gross liability position	42,000,000		42,000,000
Cash [Member]
Derivatives, Fair Value [Line Items]
Estimated fair value of securities collateral provided for over-the-counter derivatives with credit-contingent provisions in gross liability position	$ 0		$ 0		$ 0