Changes in Carrying Amount of Goodwill as Allocated to Reportable Segments (Detail) (USD $) In Millions	9 Months Ended
Sep. 30, 2011	Sep. 30, 2011 Investor Services	Sep. 30, 2011 Institutional Services	Dec. 31, 2010 Institutional Services
Goodwill [Line Items]
Balance at December 31, 2010	$ 631	$ 446	$ 185	$ 185
Goodwill acquired during the period	507	507
Balance at September 30, 2011	$ 1,138	$ 953	$ 185	$ 185

Carrying amount as of the balance sheet date, which is the cumulative amount paid and (if applicable) the fair value of any noncontrolling interest in the acquiree, adjusted for any amortization recognized prior to the adoption of any changes in generally accepted accounting principles (as applicable) and for any impairment charges, in excess of the fair value of net assets acquired in one or more business combination transactions.

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