Derivative Instruments (Effect Of Derivative Instruments On Consolidated Statements Of Operations) (Detail) (Nondesignated [Member], USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Derivative [Line Items]
Net gain/(loss) recognized in income	$ 16	$ 275	$ 390	$ 96
Unrealized Gains Losses On Insured Derivatives [Member] | Credit Default Swap [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	48	287	848	1,502
Unrealized Gains Losses On Insured Derivatives [Member] | All Other [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income		(2)	15	60
Realized Gains Losses And Other Settlements On Insured Derivatives [Member] | Credit Default Swap [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	(24)	(28)	(387)	(1,548)
Realized Gains Losses And Other Settlements On Insured Derivatives [Member] | All Other [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income			(30)
Foreign Exchange And Other Derivative Financial Instruments [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	(7)	17	(52)	58
Foreign Exchange And Other Derivative Financial Instruments [Member] | Currency Swap [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income		(1)		1
Foreign Exchange And Other Derivative Financial Instruments [Member] | All Other [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	(5)		(8)
Foreign Exchange And Other Derivative Financial Instruments Attributable To V I E [Member] | Interest Rate Swaps V I E [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income		2		17
Foreign Exchange And Other Derivative Financial Instruments Attributable To V I E [Member] | Currency Swaps Vie [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	$ 4	$ 0	$ 4	$ 6