Business Segments (Summary Of Segments Within Wind-Down Operations) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011		Dec. 31, 2011
Segment Reporting Information [Line Items]
Total revenues	$ 281		$ 1,120		$ 1,703		$ (390)
Total expenses	338		375		944		775
Income (loss) before income taxes	(57)		745		759		(1,165)
Identifiable assets	22,132		29,370		22,132		29,370		26,873
Non Variable Interest Entities [Member]
Segment Reporting Information [Line Items]
Revenues	225	[1]	284	[1]	683	[1]	802	[1]
Net gains (losses) on financial instruments at fair value and foreign exchange	7		13		(18)		(114)
Net investment losses related to other-than-temporary impairments	(8)		(11)		(105)		(44)
Net gains (losses) on extinguishment of debt							26
Operating	80		88		343		277
Other net realized gains (losses)	1		1		7		6
Interest	69		75		214		225
Variable Interest Entity [Member]
Segment Reporting Information [Line Items]
Identifiable assets	8,200				8,200				10,900
Net gains (losses) on financial instruments at fair value and foreign exchange	44		88		(17)		3
Revenues of consolidated VIEs	77		110		83		64
Net gains (losses) on extinguishment of debt	16				49
Other net realized gains (losses)			5				8
Interest	13		15		43		45
Expenses of consolidated VIEs	18		22		57		69
Asset / Liability Products [Member]
Segment Reporting Information [Line Items]
Inter-segment revenues	(1)	[2]	(3)	[2]	(15)	[2]	(9)	[2]
Total revenues	(32)		28		(187)		(137)
Inter-segment expenses	3	[2]	9	[2]	16	[2]	25	[2]
Total expenses	26		36		92		109
Income (loss) before income taxes	(58)		(8)		(279)		(246)
Identifiable assets	2,219		3,982		2,219		3,982
Asset / Liability Products [Member] | Non Variable Interest Entities [Member]
Segment Reporting Information [Line Items]
Revenues	9	[3]	23	[3]	44	[3]	70	[3]
Net gains (losses) on financial instruments at fair value and foreign exchange	(40)		11		(160)		(206)
Net investment losses related to other-than-temporary impairments			(1)		(56)		(30)
Net gains (losses) on extinguishment of debt							24
Operating	1				4		2
Other net realized gains (losses)							4
Interest	22		27		72		82
Asset / Liability Products [Member] | Variable Interest Entity [Member]
Segment Reporting Information [Line Items]
Revenues of consolidated VIEs			(2)				10
Conduits [Member]
Segment Reporting Information [Line Items]
Inter-segment revenues			(1)	[2]	(2)	[2]	(3)	[2]
Total revenues	20		4		58		12
Inter-segment expenses	36	[2]	(3)	[2]	71	[2]	(1)	[2]
Total expenses	39		5		82		14
Income (loss) before income taxes	(19)		(1)		(24)		(2)
Identifiable assets	693		1,574		693		1,574
Conduits [Member] | Non Variable Interest Entities [Member]
Segment Reporting Information [Line Items]
Revenues			(2)	[3]
Operating			2
Interest			1
Conduits [Member] | Variable Interest Entity [Member]
Segment Reporting Information [Line Items]
Revenues of consolidated VIEs	20		7		60		15
Expenses of consolidated VIEs	3		5		11		15
Eliminations [Member]
Segment Reporting Information [Line Items]
Inter-segment revenues					(2)	[2]
Total revenues					(2)
Income (loss) before income taxes					(2)
Identifiable assets	(51)				(51)
Wind-Down Operations [Member]
Segment Reporting Information [Line Items]
Inter-segment revenues	(1)	[2],[4]	(4)	[2],[4]	(19)	[2],[4]	(12)	[2],[4]
Total revenues	(12)		32		(131)		(125)
Inter-segment expenses	39	[2],[4]	6	[2],[4]	87	[2],[4]	24	[2],[4]
Total expenses	65		41		174		123
Income (loss) before income taxes	(77)		(9)		(305)		(248)
Identifiable assets	2,861		5,556		2,861		5,556
Wind-Down Operations [Member] | Non Variable Interest Entities [Member]
Segment Reporting Information [Line Items]
Revenues	9	[1],[3]	21	[1],[3]	44	[1],[3]	70	[1],[3]
Net gains (losses) on financial instruments at fair value and foreign exchange	(40)		11		(160)		(206)
Net investment losses related to other-than-temporary impairments			(1)		(56)		(30)
Net gains (losses) on extinguishment of debt							24
Operating	1		2		4		2
Other net realized gains (losses)							4
Interest	22		28		72		82
Wind-Down Operations [Member] | Variable Interest Entity [Member]
Segment Reporting Information [Line Items]
Revenues of consolidated VIEs	20		5		60		25
Expenses of consolidated VIEs	$ 3		$ 5		$ 11		$ 15

[1] Represents the sum of third-party financial guarantee net premiums earned, net investment income, insurance-related fees and reimbursements, investment management fees and other fees.

[2] Represents intercompany asset management fees and expenses plus intercompany interest income and expense pertaining to intercompany debt.

[3] Represents the sum of third-party interest income, investment management services fees and other fees.

[4] Represents intercompany premium income and expense, intercompany asset management fees and expenses, and intercompany interest income and expense pertaining to intercompany receivables and payables.