Variable Interest Entities - Securitization Activity (Details 4) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Variable Interest Entity (VIE) or Potential VIE, Information Unavailability [Member] \| Residential Mortgage [Member]
Securitization activity [Abstract]
Principal securitized	$ 616	$ 0
All cash flows during the period:
Proceeds from new securitizations	634	0
Servicing fees collected	127	180
Purchases of previously transferred financial assets (or the underlying collateral)	252	59
Cash flows received on the interests that continue to be held by the Firm	25	52
Variable Interest Entity (VIE) or Potential VIE, Information Unavailability [Member] \| Commercial Mortgage Backed Securities
Securitization activity [Abstract]
Principal securitized	2,206	0
All cash flows during the period:
Proceeds from new securitizations	2,277	0
Servicing fees collected	1	1
Purchases of previously transferred financial assets (or the underlying collateral)	0	0
Cash flows received on the interests that continue to be held by the Firm	64	43
Fair Value, Inputs, Level 2 [Member] \| Commercial Mortgage Backed Securities
All cash flows during the period:
Proceeds from new securitizations	2,100
Fair Value, Inputs, Level 2 [Member] \| Commercial Mortgage [Member]
All cash flows during the period:
Proceeds from new securitizations	207
Fair Value, Inputs, Level 2 [Member] \| Residential and commercial mortgage securitizations
All cash flows during the period:
Proceeds from new securitizations	$ 634

Cash Flows between a transferor and a transferee attributable to newly transferred assets related to either 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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Cash Flows between a transferor and a transferee attributable to purchases of previously transferred financial assets (or its underlying collateral) 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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- Definition

Cash flows between transferor and a transferee attributable to the transferor's interests related to 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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- Definition

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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