HEDGES AND OTHER DERIVATIVE FINANCIAL INSTRUMENTS - Impact of Derivative Instruments Held by Consolidated Funds on Condensed Consolidated Statements of Operations (Detail) (Not designated as hedging instrument [Member], Net Investment Hedging [Member], Consolidated funds [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Derivatives, Fair Value [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ 5,276	$ 69,196	$ 22,901	$ 150,047
Unrealized Gain (Loss) on Derivatives	(208,769)	(139,419)	8,560	(101,015)
Total return, credit-default and interest-rate swaps [Member]
Derivatives, Fair Value [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(1,235)	28,849	2,648	59,313
Unrealized Gain (Loss) on Derivatives	19,637	2,189	44,396	38,311
Foreign currency forward contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative, Gain (Loss) on Derivative, Net	9,382	40,148	28,934	103,052
Unrealized Gain (Loss) on Derivatives	(222,589)	(135,228)	(38,598)	(137,422)
Options and futures [Member]
Derivatives, Fair Value [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(2,871)	199	(8,681)	(12,318)
Unrealized Gain (Loss) on Derivatives	$ (5,817)	$ (6,380)	$ 2,762	$ (1,904)