Derivative Instruments (Effect Of Derivative Instruments On Consolidated Statements Of Operations) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Nondesignated [Member]
Derivative [Line Items]
Net Gain (Loss) Recognized in Income	$ (137)	$ 724	$ (180)	$ 1,059
Fair Value Hedging [Member]
Derivative [Line Items]
Gain (Loss) Recognized in Income on Derivative		10	0	37
Gain (Loss) Recognized in Income on Hedged Item		(10)	0	(37)
Net Gain (Loss) Recognized in Income		(1)	0	(2)
Unrealized Gains Losses On Insured Derivatives [Member] | Credit Default Swap [Member] | Nondesignated [Member]
Derivative [Line Items]
Net Gain (Loss) Recognized in Income	1,318	1,202	1,216	1,502
Unrealized Gains Losses On Insured Derivatives [Member] | All Other [Member] | Nondesignated [Member]
Derivative [Line Items]
Net Gain (Loss) Recognized in Income	32	1	61	3
Unrealized Gains Losses On Insured Derivatives [Member] | Insured Swaps [Member] | Nondesignated [Member]
Derivative [Line Items]
Net Gain (Loss) Recognized in Income	0		0	1
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	(1,532)	(428)	(1,520)	(432)
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	38	(60)	41	(50)
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		10	0	37
Gain (Loss) Recognized in Income on Hedged Item		(10)	0	(37)
Net Gain (Loss) Recognized in Income		0	0	0
Foreign Exchange And Other Derivative Financial Instruments [Member] | Currency Swap [Member] | Nondesignated [Member]
Derivative [Line Items]
Net Gain (Loss) Recognized in Income	0	2	2	0
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	0	10	14	31
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	7	(2)	6	(3)
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	(1)	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	0
Gain (Loss) Recognized in Income on Hedged Item		0	0	0
Net Gain (Loss) Recognized in Income		$ (1)	$ 0	$ (2)