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, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Net Gain (Loss) Recognized in Income	$ 724	$ (148)	$ 1,059	$ (2,017)
Fair Value Hedging [Member]
Derivative [Line Items]
Gain (Loss) Recognized in Income on Derivative	10	8	37	4
Gain (Loss) Recognized in Income on Hedged Item	(10)	(8)	(37)	(4)
Net Gain (Loss) Recognized in Income	(1)	(3)	(2)	(5)
Interest Rate Swap [Member] | Fair Value Hedging [Member]
Derivative [Line Items]
Gain (Loss) Recognized in Income on Derivative	10	8	37	2
Gain (Loss) Recognized in Income on Hedged Item	(10)	(8)	(37)	(2)
Currency Swap [Member] | Fair Value Hedging [Member]
Derivative [Line Items]
Gain (Loss) Recognized in Income on Derivative				2
Gain (Loss) Recognized in Income on Hedged Item				(2)
Unrealized Gains (Losses) On Insured Derivatives [Member] | Insured Credit Default Swaps [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Net Gain (Loss) Recognized in Income	1,202	140	1,502	(1,272)
Unrealized Gains (Losses) On Insured Derivatives [Member] | All Other [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Net Gain (Loss) Recognized in Income	1	(24)	3	(35)
Unrealized Gains (Losses) On Insured Derivatives [Member] | Insured Swaps [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Net Gain (Loss) Recognized in Income			1
Realized Gains (Losses) And Other Settlements On Insured Derivatives [Member] | Insured Credit Default Swaps [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Net Gain (Loss) Recognized in Income	(428)	(191)	(432)	(546)
Foreign Exchange and Other Derivative Financial Instruments [Member] | Non-Insured Credit Default Swaps [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Net Gain (Loss) Recognized in Income		(1)	(1)	(2)
Foreign Exchange and Other Derivative Financial Instruments [Member] | Interest Rate Swap [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Net Gain (Loss) Recognized in Income	(60)	(53)	(50)	(51)
Foreign Exchange and Other Derivative Financial Instruments [Member] | Currency Swap [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Net Gain (Loss) Recognized in Income	2	(2)		(7)
Foreign Exchange and Other Derivative Financial Instruments [Member] | All Other [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Net Gain (Loss) Recognized in Income		1	11
Net Gains (Losses) On Financial Instruments At Fair Value And Foreign Exchange-VIE [Member] | Non-Insured Credit Default Swaps-VIE [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Net Gain (Loss) Recognized in Income		7	(1)	(150)
Net Gains (Losses) On Financial Instruments At Fair Value And Foreign Exchange-VIE [Member] | Interest Rate Swaps-VIE [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Net Gain (Loss) Recognized in Income	10	(22)	31	49
Net Gains (Losses) On Financial Instruments At Fair Value And Foreign Exchange-VIE [Member] | Currency Swaps-VIE [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Net Gain (Loss) Recognized in Income	(2)	(4)	(3)	(2)
Net Gains (Losses) On Financial Instruments At Fair Value And Foreign Exchange-VIE [Member] | All Other-VIE [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Net Gain (Loss) Recognized in Income	(1)	1	(2)	(1)
Interest Income (Expense) [Member] | Interest Rate Swap [Member] | Fair Value Hedging [Member]
Derivative [Line Items]
Net Gain (Loss) Recognized in Income	$ (1)	$ (3)	$ (2)	$ (5)