Fair Value Disclosures (Liabilities Measured At Fair Value On Recurring Basis) (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral liabilities under securities lending agreements	$ 22,562		$ 20,918
Other liabilities	17	[1]	26	[1]
Total liabilities measured at fair value	24,422		22,518
Variable Interest Entity, Primary Beneficiary [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Borrowings of consolidated VIEs	1,843		1,574
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral liabilities under securities lending agreements	18,367		14,092
Other liabilities	13	[1]	15	[1]
Total liabilities measured at fair value	18,380		14,107
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral liabilities under securities lending agreements	4,195		6,826
Other liabilities	4	[1]	11	[1]
Total liabilities measured at fair value	4,199		6,837
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities measured at fair value	1,843		1,574
Significant Unobservable Inputs (Level 3) [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Borrowings of consolidated VIEs	$ 1,843		$ 1,574

[1] Amounts include credit default swap (Pillars) (see Note 7, Derivatives and Hedging, for more information) and securities sold short within consolidated sponsored investment funds recorded within other liabilities on the condensed consolidated statement of financial condition.