Business Segments (Summary Of Segments Within Wind-Down Operations) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012		Dec. 31, 2012
Segment Reporting Information [Line Items]
Net gains (losses) on extinguishment of debt	$ 4
Total revenues	219		383
Total expenses	4		362
Income (loss) before income taxes	215		21
Identifiable assets	21,592		26,126		21,724
Non Variable Interest Entities [Member]
Segment Reporting Information [Line Items]
Net gains (losses) on extinguishment of debt	4
Revenues	164	[1]	206	[1]
Net gains (losses) on financial instruments at fair value and foreign exchange	63		(19)
Net investment losses related to other- than-temporary impairments			(94)
Operating	122		171
Interest	60		73
Variable Interest Entity [Member]
Segment Reporting Information [Line Items]
Revenues of consolidated VIEs	49		(10)
Expenses of consolidated VIEs	16		21
Identifiable assets	8,300				8,300
Net gains (losses) on financial instruments at fair value and foreign exchange	33		(27)
Interest	12		15
Asset/Liability Products [Member]
Segment Reporting Information [Line Items]
Net gains (losses) on extinguishment of debt	4
Inter-segment revenues	(2)	[2]	4	[2]
Total revenues	14		(111)
Inter-segment expenses	2	[2]	8	[2]
Total expenses	22		35
Income (loss) before income taxes	(8)		(146)
Identifiable assets	1,822		3,610
Asset/Liability Products [Member] | Non Variable Interest Entities [Member]
Segment Reporting Information [Line Items]
Revenues	9	[3]	19	[3]
Net gains (losses) on financial instruments at fair value and foreign exchange	3		(80)
Net investment losses related to other- than-temporary impairments			(54)
Operating			1
Interest	20		26
Conduits [Member]
Segment Reporting Information [Line Items]
Inter-segment revenues			(1)	[2]
Total revenues	2		3
Inter-segment expenses	11	[2]
Total expenses	13		4
Income (loss) before income taxes	(11)		(1)
Identifiable assets	692		1,177
Conduits [Member] | Variable Interest Entity [Member]
Segment Reporting Information [Line Items]
Revenues of consolidated VIEs	2		4
Expenses of consolidated VIEs	2		4
Eliminations [Member]
Segment Reporting Information [Line Items]
Identifiable assets	(30)		(55)
Wind-Down Operations [Member]
Segment Reporting Information [Line Items]
Net gains (losses) on extinguishment of debt	4
Inter-segment revenues	(2)	[2],[4]	3	[2],[4]
Total revenues	16		(108)
Inter-segment expenses	13	[2],[4]	8	[2],[4]
Total expenses	35		39
Income (loss) before income taxes	(19)		(147)
Identifiable assets	2,484		4,732
Wind-Down Operations [Member] | Non Variable Interest Entities [Member]
Segment Reporting Information [Line Items]
Revenues	9	[1],[3]	19	[1],[3]
Net gains (losses) on financial instruments at fair value and foreign exchange	3		(80)
Net investment losses related to other- than-temporary impairments			(54)
Operating			1
Interest	20		26
Wind-Down Operations [Member] | Variable Interest Entity [Member]
Segment Reporting Information [Line Items]
Revenues of consolidated VIEs	2		4
Expenses of consolidated VIEs	$ 2		$ 4

[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.