Fair Value Measurement- Assets Measured at Fair Value on Nonrecurring Basis (Detail) (Fair Value, Measurements, Nonrecurring, USD $) In Millions, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans	$ 199	[1]	$ 206	[1]
Other assets	52	[2]	79	[2]
Subtotal assets of consolidated investment management funds, at fair value	251		285
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans	178	[1]	183	[1]
Other assets	52	[2]	79	[2]
Subtotal assets of consolidated investment management funds, at fair value	230		262
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans	21	[1]	23	[1]
Subtotal assets of consolidated investment management funds, at fair value	$ 21		$ 23

[1] During the quarters ended March 31, 2013 and Dec. 31, 2012, the fair value of these loans was reduced $2 million and $2 million, based on the fair value of the underlying collateral as allowed by ASC 310, Accounting by Creditors for Impairment of a loan, with an offset to the allowance for credit losses.

[2] Includes other assets received in satisfaction of debt and loans held for sale. Loans held for sale are carried on the balance sheet at the lower of cost or market value.