INVESTMENTS - Fair Value (Details) $ in Thousands	Mar. 31, 2022 USD ($) investment	Dec. 31, 2021 USD ($) investment
Schedule Of Investments In Marketable Securities [Line Items]
Investments, fair value that exceeds threshold | investment	0	0
Investments, percentage of net assets, threshold percentage	5.00%	5.00%
Consolidated Funds
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 10,513,780	$ 9,995,100
Debt securities, fair value as a percentage of investments of consolidated funds	85.80%	87.20%
Equity securities, fair value	$ 1,705,431	$ 1,427,961
Equity securities, fair value as a percentage of investments of consolidated funds	13.90%	12.50%
Real estate investments, at fair value	$ 36,887	$ 33,834
Real estate, fair value as a percentage of investments of consolidated funds	0.30%	0.30%
Investments, at fair value	$ 12,256,098	$ 11,456,895
Total investments, fair value as a percentage of investments of consolidated funds	100.00%	100.00%
Consolidated Funds | United States:
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 5,710,345	$ 5,301,713
Debt securities, fair value as a percentage of investments of consolidated funds	46.50%	46.30%
Total debt securities, cost	$ 5,781,052	$ 5,303,858
Equity securities, fair value	$ 1,290,428	$ 1,147,619
Equity securities, fair value as a percentage of investments of consolidated funds	10.50%	10.00%
Total equity securities, cost	$ 1,007,406	$ 1,086,667
Real estate investments, at fair value	$ 0	$ 0
Real estate, fair value as a percentage of investments of consolidated funds	0.00%	0.00%
Real estate securities, cost	$ 0	$ 0
Consolidated Funds | United States: | Communication services
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 632,188	$ 635,930
Debt securities, fair value as a percentage of investments of consolidated funds	5.20%	5.60%
Equity securities, fair value	$ 63,485	$ 54,635
Equity securities, fair value as a percentage of investments of consolidated funds	0.50%	0.50%
Consolidated Funds | United States: | Consumer discretionary
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 755,434	$ 665,405
Debt securities, fair value as a percentage of investments of consolidated funds	6.20%	5.80%
Equity securities, fair value	$ 148,153	$ 126,978
Equity securities, fair value as a percentage of investments of consolidated funds	1.20%	1.10%
Consolidated Funds | United States: | Consumer staples
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 258,509	$ 190,391
Debt securities, fair value as a percentage of investments of consolidated funds	2.10%	1.70%
Consolidated Funds | United States: | Energy
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 358,067	$ 354,585
Debt securities, fair value as a percentage of investments of consolidated funds	2.90%	3.10%
Equity securities, fair value	$ 438,506	$ 369,912
Equity securities, fair value as a percentage of investments of consolidated funds	3.60%	3.20%
Consolidated Funds | United States: | Financials
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 507,025	$ 463,412
Debt securities, fair value as a percentage of investments of consolidated funds	4.10%	4.00%
Equity securities, fair value	$ 191,637	$ 151,501
Equity securities, fair value as a percentage of investments of consolidated funds	1.60%	1.30%
Real estate investments, at fair value	$ 0	$ 0
Real estate, fair value as a percentage of investments of consolidated funds	0.00%	0.00%
Consolidated Funds | United States: | Health care
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 452,332	$ 459,713
Debt securities, fair value as a percentage of investments of consolidated funds	3.70%	4.00%
Equity securities, fair value	$ 42,397	$ 33,475
Equity securities, fair value as a percentage of investments of consolidated funds	0.30%	0.30%
Consolidated Funds | United States: | Industrials
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 1,033,990	$ 891,850
Debt securities, fair value as a percentage of investments of consolidated funds	8.40%	7.80%
Equity securities, fair value	$ 237,983	$ 246,856
Equity securities, fair value as a percentage of investments of consolidated funds	1.90%	2.20%
Consolidated Funds | United States: | Information technology
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 664,185	$ 685,959
Debt securities, fair value as a percentage of investments of consolidated funds	5.40%	6.00%
Consolidated Funds | United States: | Materials
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 504,009	$ 436,434
Debt securities, fair value as a percentage of investments of consolidated funds	4.10%	3.80%
Equity securities, fair value	$ 82,273	$ 82,273
Equity securities, fair value as a percentage of investments of consolidated funds	0.70%	0.70%
Consolidated Funds | United States: | Real estate
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 215,600	$ 202,131
Debt securities, fair value as a percentage of investments of consolidated funds	1.80%	1.80%
Real estate investments, at fair value	$ 0	$ 0
Real estate, fair value as a percentage of investments of consolidated funds	0.00%	0.00%
Consolidated Funds | United States: | Utilities
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 315,793	$ 305,220
Debt securities, fair value as a percentage of investments of consolidated funds	2.60%	2.70%
Equity securities, fair value	$ 85,994	$ 81,989
Equity securities, fair value as a percentage of investments of consolidated funds	0.70%	0.70%
Consolidated Funds | United States: | Other
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 13,213	$ 10,683
Debt securities, fair value as a percentage of investments of consolidated funds	0.10%	0.10%
Consolidated Funds | Europe:
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 4,189,816	$ 4,286,363
Debt securities, fair value as a percentage of investments of consolidated funds	34.10%	37.40%
Total debt securities, cost	$ 4,256,220	$ 4,289,708
Equity securities, fair value	$ 251,558	$ 150,381
Equity securities, fair value as a percentage of investments of consolidated funds	2.10%	1.30%
Total equity securities, cost	$ 219,444	$ 119,114
Real estate investments, at fair value	$ 36,887	$ 33,834
Real estate, fair value as a percentage of investments of consolidated funds	0.30%	0.30%
Real estate securities, cost	$ 38,874	$ 34,927
Consolidated Funds | Europe: | Communication services
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 749,449	$ 756,728
Debt securities, fair value as a percentage of investments of consolidated funds	6.10%	6.60%
Consolidated Funds | Europe: | Consumer discretionary
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 846,533	$ 915,535
Debt securities, fair value as a percentage of investments of consolidated funds	6.90%	8.00%
Equity securities, fair value	$ 114,679	$ 102,919
Equity securities, fair value as a percentage of investments of consolidated funds	0.90%	0.90%
Consolidated Funds | Europe: | Consumer staples
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 215,726	$ 206,590
Debt securities, fair value as a percentage of investments of consolidated funds	1.80%	1.80%
Equity securities, fair value	$ 28,729	$ 0
Equity securities, fair value as a percentage of investments of consolidated funds	0.20%	0.00%
Consolidated Funds | Europe: | Energy
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 1,024	$ 1,251
Debt securities, fair value as a percentage of investments of consolidated funds	0.00%	0.00%
Consolidated Funds | Europe: | Financials
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 97,529	$ 98,126
Debt securities, fair value as a percentage of investments of consolidated funds	0.80%	0.90%
Equity securities, fair value	$ 29,178	$ 19,987
Equity securities, fair value as a percentage of investments of consolidated funds	0.20%	0.20%
Consolidated Funds | Europe: | Health care
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 703,823	$ 751,936
Debt securities, fair value as a percentage of investments of consolidated funds	5.70%	6.60%
Equity securities, fair value	$ 89	$ 0
Equity securities, fair value as a percentage of investments of consolidated funds	0.00%	0.00%
Consolidated Funds | Europe: | Industrials
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 659,808	$ 656,033
Debt securities, fair value as a percentage of investments of consolidated funds	5.40%	5.70%
Equity securities, fair value	$ 78,883	$ 27,475
Equity securities, fair value as a percentage of investments of consolidated funds	0.60%	0.20%
Consolidated Funds | Europe: | Information technology
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 372,578	$ 383,041
Debt securities, fair value as a percentage of investments of consolidated funds	3.00%	3.30%
Consolidated Funds | Europe: | Materials
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 496,064	$ 466,181
Debt securities, fair value as a percentage of investments of consolidated funds	4.00%	4.10%
Consolidated Funds | Europe: | Real estate
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 32,766	$ 34,116
Debt securities, fair value as a percentage of investments of consolidated funds	0.30%	0.30%
Real estate investments, at fair value	$ 36,887	$ 33,834
Real estate, fair value as a percentage of investments of consolidated funds	0.30%	0.30%
Consolidated Funds | Europe: | Utilities
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 2,192	$ 1,777
Debt securities, fair value as a percentage of investments of consolidated funds	0.00%	0.00%
Consolidated Funds | Europe: | Other
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 12,324	$ 15,049
Debt securities, fair value as a percentage of investments of consolidated funds	0.10%	0.10%
Consolidated Funds | Asia and other:
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 613,619	$ 407,024
Debt securities, fair value as a percentage of investments of consolidated funds	5.10%	3.60%
Total debt securities, cost	$ 626,545	$ 417,825
Equity securities, fair value	$ 163,423	$ 129,961
Equity securities, fair value as a percentage of investments of consolidated funds	1.40%	1.10%
Total equity securities, cost	$ 146,930	$ 120,308
Consolidated Funds | Asia and other: | Communication services
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 7,410	$ 6,087
Debt securities, fair value as a percentage of investments of consolidated funds	0.10%	0.10%
Consolidated Funds | Asia and other: | Consumer discretionary
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 77,447	$ 71,082
Debt securities, fair value as a percentage of investments of consolidated funds	0.60%	0.60%
Equity securities, fair value	$ 1,108	$ 1,057
Equity securities, fair value as a percentage of investments of consolidated funds	0.00%	0.00%
Consolidated Funds | Asia and other: | Consumer staples
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 13,014	$ 13,378
Debt securities, fair value as a percentage of investments of consolidated funds	0.10%	0.10%
Consolidated Funds | Asia and other: | Energy
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 27,375	$ 24,325
Debt securities, fair value as a percentage of investments of consolidated funds	0.20%	0.20%
Equity securities, fair value	$ 8,555	$ 8,332
Equity securities, fair value as a percentage of investments of consolidated funds	0.10%	0.10%
Consolidated Funds | Asia and other: | Financials
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 13,985	$ 14,739
Debt securities, fair value as a percentage of investments of consolidated funds	0.10%	0.10%
Consolidated Funds | Asia and other: | Health care
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 2,980	$ 4,084
Debt securities, fair value as a percentage of investments of consolidated funds	0.00%	0.00%
Consolidated Funds | Asia and other: | Industrials
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 10,642	$ 7,084
Debt securities, fair value as a percentage of investments of consolidated funds	0.10%	0.10%
Equity securities, fair value	$ 110,558	$ 81,782
Equity securities, fair value as a percentage of investments of consolidated funds	0.90%	0.70%
Consolidated Funds | Asia and other: | Information technology
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 572	$ 714
Debt securities, fair value as a percentage of investments of consolidated funds	0.00%	0.00%
Consolidated Funds | Asia and other: | Materials
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 120,201	$ 121,151
Debt securities, fair value as a percentage of investments of consolidated funds	1.00%	1.10%
Consolidated Funds | Asia and other: | Real estate
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 325,643	$ 131,155
Debt securities, fair value as a percentage of investments of consolidated funds	2.70%	1.10%
Equity securities, fair value	$ 42,960	$ 38,614
Equity securities, fair value as a percentage of investments of consolidated funds	0.40%	0.30%
Consolidated Funds | Asia and other: | Utilities
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 3,680	$ 3,743
Debt securities, fair value as a percentage of investments of consolidated funds	0.00%	0.00%
Equity securities, fair value	$ 242	$ 176
Equity securities, fair value as a percentage of investments of consolidated funds	0.00%	0.00%
Consolidated Funds | Asia and other: | Other
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 10,670	$ 9,482
Debt securities, fair value as a percentage of investments of consolidated funds	0.10%	0.10%