Asset Transfers in Which the Company has Continuing Economic Involvement (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
Cash flows on interests held	$ 8	$ 11	$ 23	$ 41
Servicing or management fees	3	3	9	11
Residential Mortgage
Cash flows on interests held	6	11	21	39
Servicing or management fees	1	1	2	3
Commercial and Corporate Loans [Member]
Cash flows on interests held	1	0	1	1
Servicing or management fees	2	2	7	8
Collateralized Debt Obligations [Member]
Cash flows on interests held	$ 1	$ 0	$ 1	$ 1

Cash flows between transferor and transferee in payment of service fees in advance, prior to or in contemplation of a securitization, asset-backed financing arrangement, or similar transfer in which the transferor will have continuing involvement with the transferred financial assets underlying the transaction (including, but not limited to, servicing, recourse, and restrictions on transferor's interests in the transferred financial assets).

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Cash Flows between a transferee and a transferor attributable to servicing fees related to a securitization, asset-backed financing arrangement, or similar transfer in which the transferor has continuing involvement with the transferred financial assets underlying the transaction (including, but not limited to, servicing, recourse, and restrictions on transferor's interests in the transferred financial assets).

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