Derivative Instruments (Credit Derivatives Sold) (Detail) (Insurance Operations [Member], USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Derivative [Line Items]
Total Notional Value of Credit Derivatives	$ 55,257	$ 73,551
Total Fair Value of Credit Derivatives	(3,302)	(5,343)
Insured Credit Default Swaps [Member]
Derivative [Line Items]
Weighted Average Remaining Expected Maturity	5.4 Years	5.6 Years
Total Notional Value of Credit Derivatives	48,880	65,557
Total Fair Value of Credit Derivatives	(3,206)	(4,716)
Insured Swaps [Member]
Derivative [Line Items]
Weighted Average Remaining Expected Maturity	20.0 Years	19.7 Years
Total Notional Value of Credit Derivatives	6,182	7,156
Total Fair Value of Credit Derivatives	(9)	(9)
All Other [Member]
Derivative [Line Items]
Weighted Average Remaining Expected Maturity	2.3 Years	2.8 Years
Total Notional Value of Credit Derivatives	195	195
Total Fair Value of Credit Derivatives	(87)	(91)
Non-Insured Credit Default Swaps-VIE [Member]
Derivative [Line Items]
Weighted Average Remaining Expected Maturity		3.6 Years
Total Notional Value of Credit Derivatives		643
Total Fair Value of Credit Derivatives		(527)
AAA [Member]
Derivative [Line Items]
Total Notional Value of Credit Derivatives	10,519	15,475
Total Fair Value of Credit Derivatives	(33)	(114)
AAA [Member] | Insured Credit Default Swaps [Member]
Derivative [Line Items]
Total Notional Value of Credit Derivatives	10,519	15,475
AA [Member]
Derivative [Line Items]
Total Notional Value of Credit Derivatives	6,080	12,229
Total Fair Value of Credit Derivatives	(78)	(116)
AA [Member] | Insured Credit Default Swaps [Member]
Derivative [Line Items]
Total Notional Value of Credit Derivatives	5,895	12,065
AA [Member] | Insured Swaps [Member]
Derivative [Line Items]
Total Notional Value of Credit Derivatives	185	164
A [Member]
Derivative [Line Items]
Total Notional Value of Credit Derivatives	9,097	10,606
Total Fair Value of Credit Derivatives	(144)	(205)
A [Member] | Insured Credit Default Swaps [Member]
Derivative [Line Items]
Total Notional Value of Credit Derivatives	5,179	6,336
A [Member] | Insured Swaps [Member]
Derivative [Line Items]
Total Notional Value of Credit Derivatives	3,918	4,270
BBB [Member]
Derivative [Line Items]
Total Notional Value of Credit Derivatives	7,997	16,631
Total Fair Value of Credit Derivatives	(436)	(1,355)
BBB [Member] | Insured Credit Default Swaps [Member]
Derivative [Line Items]
Total Notional Value of Credit Derivatives	5,989	14,042
BBB [Member] | Insured Swaps [Member]
Derivative [Line Items]
Total Notional Value of Credit Derivatives	2,008	2,589
Below Investment Grade [Member]
Derivative [Line Items]
Total Notional Value of Credit Derivatives	21,564	18,610
Total Fair Value of Credit Derivatives	(2,611)	(3,553)
Below Investment Grade [Member] | Insured Credit Default Swaps [Member]
Derivative [Line Items]
Total Notional Value of Credit Derivatives	21,298	17,639
Below Investment Grade [Member] | Insured Swaps [Member]
Derivative [Line Items]
Total Notional Value of Credit Derivatives	71	133
Below Investment Grade [Member] | All Other [Member]
Derivative [Line Items]
Total Notional Value of Credit Derivatives	195	195
Below Investment Grade [Member] | Non-Insured Credit Default Swaps-VIE [Member]
Derivative [Line Items]
Total Notional Value of Credit Derivatives		$ 643