INVESTMENTS, AT FAIR VALUE - Investments, at Fair Value (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Schedule Of Investments In Marketable Securities [Line Items]
Securities sold short, at fair value	$ (122,865)	$ (126,530)
Investments, at fair value	37,792,913	38,372,626
Fixed income securities, Fair value as a percentage of investments of consolidated funds	50.40%	50.80%
Equity Securities, Fair value as a percentage of investments of consolidated funds	49.60%	49.20%
Total investments, Percentage	100.00%	100.00%
United States [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	13,799,271	13,698,904
Equity Securities, Fair Value	12,562,961	13,281,294
United States [Member] | Consumer discretionary [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	4,558,574	5,072,283
Equity Securities, Fair Value	2,865,073	3,289,347
United States [Member] | Consumer staples [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	705,214	697,300
Equity Securities, Fair Value	461,876	444,735
United States [Member] | Energy [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	619,857	565,151
Equity Securities, Fair Value	494,730	448,412
United States [Member] | Financials [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	1,065,663	1,013,230
Equity Securities, Fair Value	5,274,052	6,001,493
United States [Member] | Health care [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	769,322	658,932
Equity Securities, Fair Value	153,835	134,239
United States [Member] | Industrials [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	1,928,011	1,957,259
Equity Securities, Fair Value	1,354,035	1,201,156
United States [Member] | Information technology [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	1,060,867	908,662
Equity Securities, Fair Value	230,370	199,003
United States [Member] | Materials [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	983,266	826,008
Equity Securities, Fair Value	1,535,207	1,407,850
United States [Member] | Telecommunication services [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	348,055	282,101
Equity Securities, Fair Value	20,290	15,022
United States [Member] | Utilities [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	1,760,442	1,717,978
Equity Securities, Fair Value	173,493	140,037
Europe [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	4,423,613	4,486,075
Equity Securities, Fair Value	3,509,528	3,475,119
Europe [Member] | Consumer discretionary [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	1,552,799	1,607,822
Equity Securities, Fair Value	148,105	117,485
Europe [Member] | Consumer staples [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	412,196	486,037
Equity Securities, Fair Value	1,193,343	1,336,420
Europe [Member] | Energy [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	268,174	272,079
Equity Securities, Fair Value	84,776	91,724
Europe [Member] | Financials [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	665,995	627,161
Equity Securities, Fair Value	1,603,677	1,553,598
Europe [Member] | Health care [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	16,878	19,585
Europe [Member] | Industrials [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	579,332	531,770
Equity Securities, Fair Value	142,833	1,388
Europe [Member] | Information technology [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	5,216	5,397
Equity Securities, Fair Value	580	335
Europe [Member] | Materials [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	704,453	717,294
Equity Securities, Fair Value	336,214	374,169
Europe [Member] | Telecommunication services [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	198,473	190,369
Europe [Member] | Utilities [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	20,097	28,561
Asia and other [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	813,089	1,303,758
Equity Securities, Fair Value	2,684,451	2,127,476
Asia and other [Member] | Consumer discretionary [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	106,229	680,273
Equity Securities, Fair Value	550,766	99,527
Asia and other [Member] | Consumer staples [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	4,243	3,615
Equity Securities, Fair Value	46,687	42,688
Asia and other [Member] | Energy [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	62,597	47,776
Equity Securities, Fair Value	206,864	213,490
Asia and other [Member] | Financials [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	21,892	22,186
Equity Securities, Fair Value	1,056,497	973,745
Asia and other [Member] | Health care [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	1,806	1,622
Equity Securities, Fair Value	75	71
Asia and other [Member] | Industrials [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	384,437	290,639
Equity Securities, Fair Value	610,115	613,020
Asia and other [Member] | Information technology [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	32,983	33,260
Equity Securities, Fair Value	64,202	75,583
Asia and other [Member] | Materials [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	62,344	92,974
Equity Securities, Fair Value	53,116	51,296
Asia and other [Member] | Telecommunication services [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	2,034	1,939
Equity Securities, Fair Value	7,612	6,044
Asia and other [Member] | Utilities [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	134,524	129,474
Equity Securities, Fair Value	88,517	52,012
Consolidated funds [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Securities sold short, at fair value	(122,865)	(126,530)
Investments, at fair value	37,792,913	38,372,626
Fixed Income Investments [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair Value	19,035,973	19,488,737
Fixed Income Investments [Member] | United States [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	36.50%	35.70%
Fixed Income Investments [Member] | United States [Member] | Consumer discretionary [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	12.10%	13.20%
Fixed Income Investments [Member] | United States [Member] | Consumer staples [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	1.90%	1.80%
Fixed Income Investments [Member] | United States [Member] | Energy [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	1.60%	1.50%
Fixed Income Investments [Member] | United States [Member] | Financials [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	2.80%	2.60%
Fixed Income Investments [Member] | United States [Member] | Health care [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	2.00%	1.70%
Fixed Income Investments [Member] | United States [Member] | Industrials [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	5.10%	5.10%
Fixed Income Investments [Member] | United States [Member] | Information technology [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	2.80%	2.40%
Fixed Income Investments [Member] | United States [Member] | Materials [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	2.60%	2.20%
Fixed Income Investments [Member] | United States [Member] | Telecommunication services [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	0.90%	0.70%
Fixed Income Investments [Member] | United States [Member] | Utilities [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	4.70%	4.50%
Fixed Income Investments [Member] | Europe [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	11.70%	11.70%
Fixed Income Investments [Member] | Europe [Member] | Consumer discretionary [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	4.10%	4.20%
Fixed Income Investments [Member] | Europe [Member] | Consumer staples [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	1.10%	1.30%
Fixed Income Investments [Member] | Europe [Member] | Energy [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	0.70%	0.70%
Fixed Income Investments [Member] | Europe [Member] | Financials [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	1.80%	1.60%
Fixed Income Investments [Member] | Europe [Member] | Health care [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	0.00%	0.00%
Fixed Income Investments [Member] | Europe [Member] | Industrials [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	1.50%	1.40%
Fixed Income Investments [Member] | Europe [Member] | Information technology [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	0.00%	0.00%
Fixed Income Investments [Member] | Europe [Member] | Materials [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	1.90%	1.90%
Fixed Income Investments [Member] | Europe [Member] | Telecommunication services [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	0.50%	0.50%
Fixed Income Investments [Member] | Europe [Member] | Utilities [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	0.10%	0.10%
Fixed Income Investments [Member] | Asia and other [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	2.20%	3.40%
Fixed Income Investments [Member] | Asia and other [Member] | Consumer discretionary [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	0.30%	1.80%
Fixed Income Investments [Member] | Asia and other [Member] | Consumer staples [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	0.00%	0.00%
Fixed Income Investments [Member] | Asia and other [Member] | Energy [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	0.20%	0.10%
Fixed Income Investments [Member] | Asia and other [Member] | Financials [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	0.10%	0.10%
Fixed Income Investments [Member] | Asia and other [Member] | Health care [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	0.00%	0.00%
Fixed Income Investments [Member] | Asia and other [Member] | Industrials [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	1.00%	0.80%
Fixed Income Investments [Member] | Asia and other [Member] | Information technology [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	0.10%	0.10%
Fixed Income Investments [Member] | Asia and other [Member] | Materials [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	0.20%	0.20%
Fixed Income Investments [Member] | Asia and other [Member] | Telecommunication services [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	0.00%	0.00%
Fixed Income Investments [Member] | Asia and other [Member] | Utilities [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Fixed income securities, Fair value as a percentage of investments of consolidated funds	0.30%	0.30%
Equity Securities [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Equity Securities, Fair Value	18,756,940	18,883,889
Securities sold short, at fair value	$ (122,865)	$ (126,530)
Equity Securities [Member] | United States [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Equity Securities, Fair value as a percentage of investments of consolidated funds	33.30%	34.60%
Equity Securities [Member] | United States [Member] | Consumer discretionary [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Equity Securities, Fair value as a percentage of investments of consolidated funds	7.60%	8.60%
Equity Securities [Member] | United States [Member] | Consumer staples [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Equity Securities, Fair value as a percentage of investments of consolidated funds	1.20%	1.20%
Equity Securities [Member] | United States [Member] | Energy [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Equity Securities, Fair value as a percentage of investments of consolidated funds	1.30%	1.20%
Equity Securities [Member] | United States [Member] | Financials [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Equity Securities, Fair value as a percentage of investments of consolidated funds	14.00%	15.60%
Equity Securities [Member] | United States [Member] | Health care [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Equity Securities, Fair value as a percentage of investments of consolidated funds	0.40%	0.30%
Equity Securities [Member] | United States [Member] | Industrials [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Equity Securities, Fair value as a percentage of investments of consolidated funds	3.60%	3.10%
Equity Securities [Member] | United States [Member] | Information technology [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Equity Securities, Fair value as a percentage of investments of consolidated funds	0.60%	0.50%
Equity Securities [Member] | United States [Member] | Materials [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Equity Securities, Fair value as a percentage of investments of consolidated funds	4.10%	3.70%
Equity Securities [Member] | United States [Member] | Telecommunication services [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Equity Securities, Fair value as a percentage of investments of consolidated funds	0.00%	0.00%
Equity Securities [Member] | United States [Member] | Utilities [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Equity Securities, Fair value as a percentage of investments of consolidated funds	0.50%	0.40%
Equity Securities [Member] | Europe [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Equity Securities, Fair value as a percentage of investments of consolidated funds	9.30%	9.10%
Equity Securities [Member] | Europe [Member] | Consumer discretionary [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Equity Securities, Fair value as a percentage of investments of consolidated funds	0.40%	0.30%
Equity Securities [Member] | Europe [Member] | Consumer staples [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Equity Securities, Fair value as a percentage of investments of consolidated funds	3.20%	3.50%
Equity Securities [Member] | Europe [Member] | Energy [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Equity Securities, Fair value as a percentage of investments of consolidated funds	0.20%	0.20%
Equity Securities [Member] | Europe [Member] | Financials [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Equity Securities, Fair value as a percentage of investments of consolidated funds	4.20%	4.10%
Equity Securities [Member] | Europe [Member] | Industrials [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Equity Securities, Fair value as a percentage of investments of consolidated funds	0.40%	0.00%
Equity Securities [Member] | Europe [Member] | Information technology [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Equity Securities, Fair value as a percentage of investments of consolidated funds	0.00%	0.00%
Equity Securities [Member] | Europe [Member] | Materials [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Equity Securities, Fair value as a percentage of investments of consolidated funds	0.90%	1.00%
Equity Securities [Member] | Asia and other [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Equity Securities, Fair value as a percentage of investments of consolidated funds	7.00%	5.50%
Equity Securities [Member] | Asia and other [Member] | Consumer discretionary [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Equity Securities, Fair value as a percentage of investments of consolidated funds	1.50%	0.30%
Equity Securities [Member] | Asia and other [Member] | Consumer staples [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Equity Securities, Fair value as a percentage of investments of consolidated funds	0.10%	0.10%
Equity Securities [Member] | Asia and other [Member] | Energy [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Equity Securities, Fair value as a percentage of investments of consolidated funds	0.50%	0.60%
Equity Securities [Member] | Asia and other [Member] | Financials [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Equity Securities, Fair value as a percentage of investments of consolidated funds	2.80%	2.50%
Equity Securities [Member] | Asia and other [Member] | Health care [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Equity Securities, Fair value as a percentage of investments of consolidated funds	0.00%	0.00%
Equity Securities [Member] | Asia and other [Member] | Industrials [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Equity Securities, Fair value as a percentage of investments of consolidated funds	1.60%	1.60%
Equity Securities [Member] | Asia and other [Member] | Information technology [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Equity Securities, Fair value as a percentage of investments of consolidated funds	0.20%	0.20%
Equity Securities [Member] | Asia and other [Member] | Materials [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Equity Securities, Fair value as a percentage of investments of consolidated funds	0.10%	0.10%
Equity Securities [Member] | Asia and other [Member] | Telecommunication services [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Equity Securities, Fair value as a percentage of investments of consolidated funds	0.00%	0.00%
Equity Securities [Member] | Asia and other [Member] | Utilities [Member]
Schedule Of Investments In Marketable Securities [Line Items]
Equity Securities, Fair value as a percentage of investments of consolidated funds	0.20%	0.10%