Derivative Instruments (Effect Of Derivative Instruments On Consolidated Statements Of Operations) (Detail) - Nondesignated [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Derivative [Line Items]
Net gain/(loss) recognized in income	$ (31)	$ 16	$ 4	$ 390
Unrealized Gains Losses On Insured Derivatives [Member] | Credit Default Swap [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	21	48	121	848
Unrealized Gains Losses On Insured Derivatives [Member] | All Other [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	0	0		15
Realized Gains Losses And Other Settlements On Insured Derivatives [Member] | Credit Default Swap [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	(18)	(24)	(30)	(387)
Realized Gains Losses And Other Settlements On Insured Derivatives [Member] | All Other [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	0	0		(30)
Foreign Exchange And Other Derivative Financial Instruments [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	(45)	(7)	(112)	(52)
Foreign Exchange And Other Derivative Financial Instruments [Member] | Currency Swap [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income		0
Foreign Exchange And Other Derivative Financial Instruments [Member] | All Other [Member]
Derivative [Line Items]
Net gain/(loss) recognized in income	(1)	(5)	2	(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	8	0	18
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	$ 4	$ 5	$ 4