Derivatives (Narrative) (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	$ 12,823,000,000		$ 13,777,000,000
Estimated Fair Value Liabilities	5,294,000,000		5,536,000,000
Maximum Amount of Future Payments under Credit Default Swaps	8,909,000,000		8,879,000,000
Estimated Fair Value of Credit Default Swaps	88,000,000		74,000,000
Derivative Instruments, Gain (Loss) [Line Items]
Embedded derivatives	1,684,000,000	1,824,000,000
Derivative Instrument Detail [Abstract]
Net amounts reclassified into net derivatives gains (losses) on discontinued cash flow hedges	0	3,000,000
Hedging exposure to variability in future cash flows for specific length of time	8 years	8 years
Accumulated Other Comprehensive Income Loss	1,400,000,000		1,300,000,000
Deferred net gains (losses) expected to be reclassified to earnings	33,000,000
Amount and Location of Gains (Losses) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss) (Effective Portion)	0	0
Immateriality of cash flow effectiveness	0	0
Cumulative foreign currency translation gain (loss) recorded in accumulated other comprehensive income (loss) for net investment in foreign operations hedges	72,000,000		(98,000,000)
Potential future recoveries available to offset maximum amount of future payments under credit default swaps	70,000,000		150,000,000
Excess securities collateral received on derivatives	19,000,000		0
Excess securities collateral provided on derivatives	422,000,000		290,000,000
Change in fair value of derivatives excluded from the assessment of hedge effectiveness	0	0
Securities collateral received which the company is permitted to sell or repledge, amount that has been sold or repledged	0
Entity Securities for which Counterparty has Right to Sell or Repledge, Fair Value of Securities Sold or Repledged	0
Over the Counter [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Excess securities collateral received on derivatives	239,000,000		161,000,000
Excess securities collateral provided on derivatives	110,000,000		0
Exchange Traded [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Excess securities collateral received on derivatives	0		0
Excess securities collateral provided on derivatives	40,000,000		40,000,000
Nonperformance Risk [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Embedded derivatives	(414,000,000)	(1,200,000,000)
Hedge Funds [Member]
Derivatives, Fair Value [Line Items]
Maximum Amount of Future Payments under Credit Default Swaps	30,000,000		10,000,000
Estimated Fair Value of Credit Default Swaps	0		0
Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Estimated Fair Value Assets	271,000,000		290,000,000
Estimated Fair Value Liabilities	$ 143,000,000		$ 114,000,000