Investments (Summary Of The Cost And Carrying Value Of Investments Classified As Available-For-Sale) (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Schedule of Investments [Line Items]
Cost	$ 182	$ 54
Gross Unrealized, Gains	11
Gross Unrealized, Losses	(1)	(2)
Carrying Value	192	52
Consolidated Sponsored Investment Funds [Member]
Schedule of Investments [Line Items]
Cost	180	52
Gross Unrealized, Gains	10
Gross Unrealized, Losses	(1)	(2)
Carrying Value	189	50
Collateralized Debt Obligations [Member]
Schedule of Investments [Line Items]
Cost	1	1
Carrying Value	1	1
Asset-backed Securities [Member]
Schedule of Investments [Line Items]
Cost	1	1
Gross Unrealized, Gains	1
Carrying Value	$ 2	$ 1

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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+ Details

- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References+ Details

- Definition

This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

+ References+ Details