Securitizations and Variable Interest Entities- Incremental Assets and Liabilities of Variable Interest Entities Included in Consolidated Financial Statements (Detail) (Variable Interest Entity, Primary Beneficiary, USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Variable Interest Entity [Line Items]
Available-for-sale	$ 500	$ 499
Trading assets	10,400	10,961
Other assets	836	520
Subtotal assets of consolidated investment management funds, at fair value	11,736	11,980
Trading liabilities	9,908	10,152
Other liabilities	492	490
Subtotal liabilities of consolidated investment management funds, at fair value	10,400	10,642
Nonredeemable noncontrolling interests of consolidated investment management funds	806	833
Investment Management Funds
Variable Interest Entity [Line Items]
Available-for-sale	0	0
Trading assets	10,400	10,961
Other assets	836	520
Subtotal assets of consolidated investment management funds, at fair value	11,236	11,481
Trading liabilities	9,908	10,152
Other liabilities	34	29
Subtotal liabilities of consolidated investment management funds, at fair value	9,942	10,181
Nonredeemable noncontrolling interests of consolidated investment management funds	806	833
Securitizations
Variable Interest Entity [Line Items]
Available-for-sale	500	499
Trading assets	0	0
Other assets	0	0
Subtotal assets of consolidated investment management funds, at fair value	500	499
Trading liabilities	0	0
Other liabilities	458	461
Subtotal liabilities of consolidated investment management funds, at fair value	458	461
Nonredeemable noncontrolling interests of consolidated investment management funds	$ 0	$ 0