Derivative Instruments (Total Fair Value Of Company's Derivative Assets And Liabilities By Instrument And Balance Sheet Location, Before Counterparty Netting) (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Derivative [Line Items]
Derivative Instruments, Designated as hedging instruments			$ 241
Derivative Instruments, Not designated as hedging instruments	58,640		87,616
Notional Amount Outstanding, Total derivatives	58,640		87,857
Derivative Liabilities [Member]
Derivative [Line Items]
Derivative Liabilities, Designated, Fair Value			(44)	[1]
Derivative Liabilities, Not designated, Fair Value	(3,425)	[2]	(6,064)	[1]
Derivative liabilities, Total derivatives	(3,425)	[2]	(6,108)	[1]
Derivative Assets [Member]
Derivative [Line Items]
Derivative Assets, Designated, Fair Value			10	[1]
Derivative Assets, Not designated, Fair Value	102	[2]	542	[1]
Derivative assets, Total derivatives	102	[2]	552	[1]
Insured Credit Default Swaps [Member]
Derivative [Line Items]
Derivative Instruments, Not designated as hedging instruments	47,320		66,851
Insured Credit Default Swaps [Member] | Derivative Liabilities [Member]
Derivative [Line Items]
Derivative Liabilities, Not designated, Fair Value	(2,858)	[2]	(4,708)	[1]
Insured Swaps [Member]
Derivative [Line Items]
Derivative Instruments, Not designated as hedging instruments	5,817		7,156
Insured Swaps [Member] | Derivative Liabilities [Member]
Derivative [Line Items]
Derivative Liabilities, Not designated, Fair Value	(8)	[2]	(9)	[1]
Non-Insured Credit Default Swaps [Member]
Derivative [Line Items]
Derivative Instruments, Not designated as hedging instruments	10		30
Non-Insured Credit Default Swaps [Member] | Other Assets [Member]
Derivative [Line Items]
Derivative Assets, Not designated, Fair Value			1	[1]
Interest Rate Swaps [Member]
Derivative [Line Items]
Derivative Instruments, Designated as hedging instruments			241
Derivative Instruments, Not designated as hedging instruments	1,637		2,706
Interest Rate Swaps [Member] | Derivative Liabilities [Member]
Derivative [Line Items]
Derivative Liabilities, Designated, Fair Value			(44)	[1]
Derivative Liabilities, Not designated, Fair Value	(290)	[2]	(401)	[1]
Interest Rate Swaps [Member] | Other Assets [Member]
Derivative [Line Items]
Derivative Assets, Designated, Fair Value			10	[1]
Derivative Assets, Not designated, Fair Value	94	[2]	84	[1]
Interest Rate Swaps-VIE [Member]
Derivative [Line Items]
Derivative Instruments, Not designated as hedging instruments	2,728		4,878
Interest Rate Swaps-VIE [Member] | Derivative Liabilities-VIE [Member]
Derivative [Line Items]
Derivative Liabilities, Not designated, Fair Value	(141)	[2]	(281)	[1]
Interest Rate Swaps-Embedded [Member]
Derivative [Line Items]
Derivative Instruments, Not designated as hedging instruments	483		480
Interest Rate Swaps-Embedded [Member] | Medium-Term Notes [Member]
Derivative [Line Items]
Derivative Assets, Not designated, Fair Value	8	[2]	7	[1]
Derivative Liabilities, Not designated, Fair Value	(35)	[2]	(14)	[1]
Currency Swap [Member]
Derivative [Line Items]
Derivative Instruments, Not designated as hedging instruments	40		62
Currency Swap [Member] | Derivative Liabilities [Member]
Derivative [Line Items]
Derivative Liabilities, Not designated, Fair Value	(3)	[2]	(4)	[1]
Currency Swaps-VIE [Member]
Derivative [Line Items]
Derivative Instruments, Not designated as hedging instruments	110		123
Currency Swaps-VIE [Member] | Derivative Liabilities-VIE [Member]
Derivative [Line Items]
Derivative Liabilities, Not designated, Fair Value	(21)	[2]	(17)	[1]
All Other [Member]
Derivative [Line Items]
Derivative Instruments, Not designated as hedging instruments	195		3,465
All Other [Member] | Derivative Liabilities [Member]
Derivative [Line Items]
Derivative Liabilities, Not designated, Fair Value	(68)	[2]	(91)	[1]
All Other-VIE [Member]
Derivative [Line Items]
Derivative Instruments, Not designated as hedging instruments	280		472
All Other-VIE [Member] | Derivative Assets-VIE [Member]
Derivative [Line Items]
Derivative Assets, Not designated, Fair Value			3	[1]
All Other-Embedded [Member]
Derivative [Line Items]
Derivative Instruments, Not designated as hedging instruments	20		121
All Other-Embedded [Member] | Derivative Liabilities, Other Investments [Member]
Derivative [Line Items]
Derivative Liabilities, Not designated, Fair Value	(1)	[2]	(12)	[1]
Non-Insured Credit Default Swaps-VIE [Member]
Derivative [Line Items]
Derivative Instruments, Not designated as hedging instruments			1,272
Non-Insured Credit Default Swaps-VIE [Member] | Derivative Liabilities-VIE [Member]
Derivative [Line Items]
Derivative Liabilities, Not designated, Fair Value			(527)	[1]
Non-Insured Credit Default Swaps-VIE [Member] | Derivative Assets-VIE [Member]
Derivative [Line Items]
Derivative Assets, Not designated, Fair Value			$ 447	[1]

[1] In accordance with the accounting guidance for derivative instruments and hedging activities, the balance sheet location of the Company's embedded derivative instruments is determined by the location of the related host contract

[2] In accordance with the accounting guidance for derivative instruments and hedging activities, the balance sheet location of the Company's embedded derivative instruments is determined by the location of the related host contract.