Derivative Instruments (Effect Of Derivative Instruments On Consolidated Statements Of Operations) (Detail) (Nondesignated [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Derivative [Line Items]
Net gain/(loss) recognized in income	$ 398	$ 325	$ 1,445
Unrealized Gains Losses On Insured Derivatives [Member] | Credit Default Swap [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	888	1,725	1,847
Unrealized Gains Losses On Insured Derivatives [Member] | All Other [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	15	52	22
Unrealized Gains Losses On Insured Derivatives [Member] | Insured Swaps [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income			1
Realized Gains Losses And Other Settlements On Insured Derivatives [Member] | Credit Default Swap [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	(413)	(1,545)	(406)
Realized Gains Losses And Other Settlements On Insured Derivatives [Member] | All Other [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	(31)
Foreign Exchange And Other Derivative Financial Instruments [Member] | Non Insured Credit Default Swaps [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income			(1)
Foreign Exchange And Other Derivative Financial Instruments [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	(78)	65	(75)
Foreign Exchange And Other Derivative Financial Instruments [Member] | Currency Swap [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income		1	(2)
Foreign Exchange And Other Derivative Financial Instruments [Member] | All Other [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	6		11
Foreign Exchange And Other Derivative Financial Instruments Attributable To V I E [Member] | Non Insured Credit Default Swaps V I E [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income			(1)
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		17	55
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	11	10	(4)
Foreign Exchange And Other Derivative Financial Instruments Attributable To V I E [Member] | All Other V I E [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income			$ (2)