FAIR VALUE FAIR VALUE - Financial Instruments Held by Consolidated Funds (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	$ 37,792,913	$ 38,372,626
Securities Sold, Not yet Purchased, Fair Value Disclosure	(122,865)	(126,530)
Level I [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	4,281,590	3,367,195
Securities Sold, Not yet Purchased, Fair Value Disclosure	(122,865)	(126,530)
Level II [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	14,390,569	15,142,246
Securities Sold, Not yet Purchased, Fair Value Disclosure	0	0
Level III [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	19,120,754	19,863,185
Securities Sold, Not yet Purchased, Fair Value Disclosure	0	0
Corporate debt-bank debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	9,466,054	9,666,167
Corporate debt-bank debt [Member] | Level I [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	0	0
Corporate debt-bank debt [Member] | Level II [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	7,398,616	7,412,691
Corporate debt-bank debt [Member] | Level III [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	2,067,438	2,253,476
Corporate debt-all other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	9,569,919	9,822,570
Corporate debt-all other [Member] | Level I [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	0	0
Corporate debt-all other [Member] | Level II [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	6,657,081	6,663,519
Corporate debt-all other [Member] | Level III [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	2,912,838	3,159,051
Equities - common stock [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	11,680,252	12,519,258
Equities - common stock [Member] | Level I [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	4,101,845	3,362,742
Equities - common stock [Member] | Level II [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	330,561	1,055,465
Equities - common stock [Member] | Level III [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	7,247,846	8,101,051
Equities-preferred stock [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	654,084	654,749
Equities-preferred stock [Member] | Level I [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	3,459	2,520
Equities-preferred stock [Member] | Level II [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	2,793	2,133
Equities-preferred stock [Member] | Level III [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	647,832	650,096
Real estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	4,673,360	3,946,142
Real estate [Member] | Level I [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	174,434	0
Real estate [Member] | Level II [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	0	0
Real estate [Member] | Level III [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	4,498,926	3,946,142
Real Estate Loan Portfolio [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	1,730,384	1,737,822
Real Estate Loan Portfolio [Member] | Level I [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	0	0
Real Estate Loan Portfolio [Member] | Level II [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	0	0
Real Estate Loan Portfolio [Member] | Level III [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	1,730,384	1,737,822
Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	18,860	25,918
Other [Member] | Level I [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	1,852	1,933
Other [Member] | Level II [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	1,518	8,438
Other [Member] | Level III [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, at fair value	15,490	15,547
Options written [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets, at fair value	3,161	5,520
Options written [Member] | Level I [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets, at fair value	0	0
Options written [Member] | Level II [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets, at fair value	3,161	5,520
Options written [Member] | Level III [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets, at fair value	0	0
Swaps (net)-corporate debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets, at fair value	50,209	39,166
Swaps (net)-corporate debt [Member] | Level I [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets, at fair value	0	0
Swaps (net)-corporate debt [Member] | Level II [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, at fair value	(4,465)	(5,539)
Swaps (net)-corporate debt [Member] | Level III [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets, at fair value	54,674	44,705
Forward contracts (net) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets, at fair value	62,007
Derivative liabilities, at fair value		(93,863)
Forward contracts (net) [Member] | Level I [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets, at fair value	0
Derivative liabilities, at fair value		0
Forward contracts (net) [Member] | Level II [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets, at fair value	62,007
Derivative liabilities, at fair value		(93,863)
Forward contracts (net) [Member] | Level III [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets, at fair value	0
Derivative liabilities, at fair value		0
Futures [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets, at fair value		90
Derivative liabilities, at fair value	(739)
Futures [Member] | Level I [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets, at fair value		90
Derivative liabilities, at fair value	(739)
Futures [Member] | Level II [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets, at fair value		0
Derivative liabilities, at fair value	0
Futures [Member] | Level III [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets, at fair value		0
Derivative liabilities, at fair value	$ 0