Derivative Instruments (Effect Of Derivative Instruments On Consolidated Statements Of Operations) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Nondesignated [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	$ 275	$ (40)	$ 96	$ 1,019
Fair Value Hedging [Member]
Derivative [Line Items]
Gain/(loss) recognized in income on derivative		(12)		25
Gain/(loss) recognized in income on hedged item		12		(25)
Net gain/(loss) recognized in income		0		(3)
Unrealized Gains Losses On Insured Derivatives [Member] | Credit Default Swap [Member] | Nondesignated [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	287	(40)	1,502	1,463
Unrealized Gains Losses On Insured Derivatives [Member] | All Other [Member] | Nondesignated [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	(2)	7	60	10
Unrealized Gains Losses On Insured Derivatives [Member] | Insured Swaps [Member] | Nondesignated [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	0		0	0
Realized Gains Losses And Other Settlements On Insured Derivatives [Member] | Credit Default Swap [Member] | Nondesignated [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	(28)	12	(1,548)	(420)
Foreign Exchange And Other Derivative Financial Instruments [Member] | Non Insured Credit Default Swaps [Member] | Nondesignated [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	0	0	0	(1)
Foreign Exchange And Other Derivative Financial Instruments [Member] | Interest Rate Swap [Member] | Nondesignated [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	17	(26)	58	(76)
Foreign Exchange And Other Derivative Financial Instruments [Member] | Interest Rate Swap [Member] | Fair Value Hedging [Member]
Derivative [Line Items]
Gain/(loss) recognized in income on derivative		(12)		25
Gain/(loss) recognized in income on hedged item		12		(25)
Net gain/(loss) recognized in income		0		0
Foreign Exchange And Other Derivative Financial Instruments [Member] | Currency Swap [Member] | Nondesignated [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	(1)	1	1	1
Foreign Exchange And Other Derivative Financial Instruments [Member] | Currency Swap [Member] | Fair Value Hedging [Member]
Derivative [Line Items]
Gain/(loss) recognized in income on derivative				0
Gain/(loss) recognized in income on hedged item				0
Net gain/(loss) recognized in income				0
Foreign Exchange And Other Derivative Financial Instruments [Member] | All Other [Member] | Nondesignated [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	0	0	0	11
Foreign Exchange And Other Derivative Financial Instruments Attributable To V I E [Member] | Non Insured Credit Default Swaps V I E [Member] | Nondesignated [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	0	0	0	(1)
Foreign Exchange And Other Derivative Financial Instruments Attributable To V I E [Member] | Interest Rate Swaps V I E [Member] | Nondesignated [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	2	8	17	39
Foreign Exchange And Other Derivative Financial Instruments Attributable To V I E [Member] | Currency Swaps Vie [Member] | Nondesignated [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	0	(2)	6	(5)
Foreign Exchange And Other Derivative Financial Instruments Attributable To V I E [Member] | All Other V I E [Member] | Nondesignated [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	0	0	0	(2)
Interest Income Expense [Member] | Interest Rate Swap [Member] | Fair Value Hedging [Member]
Derivative [Line Items]
Gain/(loss) recognized in income on derivative		0		0
Gain/(loss) recognized in income on hedged item		0		0
Net gain/(loss) recognized in income		$ 0		$ (3)