Derivatives (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 1,600		$ 1,600		$ 2,370
Derivative Liability, Fair Value, Gross Liability	811		811		970
Maximum Amount of Future Payments under Credit Default Swaps	2,299		2,299		2,456
Estimated Fair Value of Credit Default Swaps	29		29		22
Derivative Instruments, Gain (Loss) [Line Items]
Embedded derivatives	(16)	91	165	270
Derivative Instrument Detail [Abstract]
Net amounts reclassified into net derivatives gains (losses) on discontinued cash flow hedges	0	0	0	0
Hedging exposure to variability in future cash flows for specific length of time			6 years		7 years
Accumulated Other Comprehensive Income (Loss)	79		79		243
Deferred net gains (losses) expected to be reclassified to earnings			(1)
Cash collateral on derivative assets	9		9		0
Cash collateral on derivative liabilities	55		55		53
Securities collateral received which the company is permitted to sell or repledge, amount that has been sold or repledged	0		0
Over The Counter [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Excess securities collateral received on derivatives	78		78		0
Excess securities collateral provided on derivatives	5		5		0
Exchange Cleared [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Excess securities collateral provided on derivatives	18		18		0
Exchange Traded [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Excess securities collateral provided on derivatives	0		0		0
Nonperformance Risk [Member] | Direct and assumed guaranteed minimum benefit [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Embedded derivatives	(12)	(110)	(139)	(212)
Nonperformance Risk [Member] | Ceded Guaranteed Minimum Benefit [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Embedded derivatives	39	202	198	241
Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	42		42		66
Derivative Liability, Fair Value, Gross Liability	$ 24		$ 24		$ 46