Business Segments (Summary Of Segments Within Wind-Down 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		Dec. 31, 2011
Segment Reporting Information [Line Items]
Total revenues	$ 1,039		$ 98		$ 1,422		$ (1,510)
Total expenses	244		245		606		400
Income (loss) before income taxes	795		(147)		816		(1,910)
Identifiable assets	22,295				22,295				26,873
Non Variable Interest Entities [Member]
Segment Reporting Information [Line Items]
Identifiable assets	22,295		31,668		22,295		31,668
Revenues	251	[1]	255	[1]	458	[1]	520	[1]
Net gains (losses) on financial instruments at fair value and foreign exchange	(6)		(103)		(25)		(127)
Net investment losses related to other-than-temporary impairments	(3)		(20)		(97)		(33)
Net gains (losses) on extinguishment of debt							26
Other net realized gains (losses)	6				6		5
Operating expenses	93		98		263		189
Interest expense	71		75		145		150
Variable Interest Entity [Member]
Segment Reporting Information [Line Items]
Identifiable assets	8,400				8,400				10,900
Net gains (losses) on financial instruments at fair value and foreign exchange	(34)		22		(61)		(85)
Net gains (losses) on extinguishment of debt	33				33
Revenues of consolidated VIEs	16		41		6		(48)
Other net realized gains (losses)			3				3
Interest expense	15		15		30		30
Expenses of consolidated VIEs	18		22		39		47
Asset / Liability Products [Member]
Segment Reporting Information [Line Items]
Inter-segment revenues	(18)	[2]	(2)	[2]	(15)	[2]	(6)	[2]
Total revenues	(44)		(129)		(156)		(165)
Inter-segment expenses	6	[2]	8	[2]	12	[2]	17	[2]
Total expenses	32		37		65		73
Income (loss) before income taxes	(76)		(166)		(221)		(238)
Identifiable assets	2,439		4,481		2,439		4,481
Asset / Liability Products [Member] | Non Variable Interest Entities [Member]
Segment Reporting Information [Line Items]
Revenues	16	[3]	23	[3]	35	[3]	47	[3]
Net gains (losses) on financial instruments at fair value and foreign exchange	(40)		(133)		(120)		(216)
Net investment losses related to other-than-temporary impairments	(2)		(18)		(56)		(29)
Net gains (losses) on extinguishment of debt							24
Other net realized gains (losses)							4
Operating expenses	3		1		3		2
Interest expense	23		28		50		54
Asset / Liability Products [Member] | Variable Interest Entity [Member]
Segment Reporting Information [Line Items]
Revenues of consolidated VIEs			1				11
Conduits [Member]
Segment Reporting Information [Line Items]
Inter-segment revenues	(1)	[2]	(1)	[2]	(2)	[2]	(2)	[2]
Total revenues	35		3		38		8
Inter-segment expenses	34	[2]			35	[2]	1	[2]
Total expenses	38		4		43		10
Income (loss) before income taxes	(3)		(1)		(5)		(2)
Identifiable assets	819		1,564		819		1,564
Conduits [Member] | Non Variable Interest Entities [Member]
Segment Reporting Information [Line Items]
Revenues			1	[3]			2	[3]
Operating expenses			(1)				(1)
Conduits [Member] | Variable Interest Entity [Member]
Segment Reporting Information [Line Items]
Revenues of consolidated VIEs	36		3		40		8
Expenses of consolidated VIEs	4		5		8		10
Eliminations [Member]
Segment Reporting Information [Line Items]
Inter-segment revenues	(2)	[2]			(2)	[2]
Total revenues	(2)				(2)
Income (loss) before income taxes	(2)				(2)
Identifiable assets	(53)		(405)		(53)		(405)
Wind-Down Operations [Member]
Segment Reporting Information [Line Items]
Inter-segment revenues	(21)	[2],[4]	(3)	[2],[4]	(19)	[2],[4]	(8)	[2],[4]
Total revenues	(11)		(126)		(120)		(157)
Inter-segment expenses	40	[2],[4]	8	[2],[4]	47	[2],[4]	18	[2],[4]
Total expenses	70		41		108		83
Income (loss) before income taxes	(81)		(167)		(228)		(240)
Identifiable assets	3,205		5,640		3,205		5,640
Wind-Down Operations [Member] | Non Variable Interest Entities [Member]
Segment Reporting Information [Line Items]
Identifiable assets	3,205		5,640		3,205		5,640
Revenues	16	[1],[3]	24	[1],[3]	35	[1],[3]	49	[1],[3]
Net gains (losses) on financial instruments at fair value and foreign exchange	(40)		(133)		(120)		(216)
Net investment losses related to other-than-temporary impairments	(2)		(18)		(56)		(29)
Net gains (losses) on extinguishment of debt							24
Other net realized gains (losses)							4
Operating expenses	3				3		1
Interest expense	23		28		50		54
Wind-Down Operations [Member] | Variable Interest Entity [Member]
Segment Reporting Information [Line Items]
Revenues of consolidated VIEs	36		4		40		19
Expenses of consolidated VIEs	$ 4		$ 5		$ 8		$ 10

[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.