INVESTMENTS - Fair Value (Details) $ in Thousands	Mar. 31, 2024 USD ($) investment	Dec. 31, 2023 USD ($) investment
Schedule Of Investments In Marketable Securities [Line Items]
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	$ 3,846,395	$ 3,322,558
Debt securities, fair value as a percentage of investments of consolidated funds	66.60%	64.80%
Equity securities, fair value	$ 1,738,700	$ 1,645,766
Equity securities, fair value as a percentage of investments of consolidated funds	30.10%	31.80%
Real estate investments, at fair value	$ 186,681	$ 175,353
Real estate, fair value as a percentage of investments of consolidated funds	3.30%	3.40%
Investments, at fair value	$ 5,771,776	$ 5,143,677
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	$ 2,820,581	$ 2,328,442
Debt securities, fair value as a percentage of investments of consolidated funds	48.90%	45.40%
Total debt securities, cost	$ 2,816,424	$ 2,341,421
Equity securities, fair value	$ 1,358,264	$ 1,281,750
Equity securities, fair value as a percentage of investments of consolidated funds	23.70%	24.80%
Total equity securities, cost	$ 1,086,131	$ 1,095,721
Real estate investments, at fair value	$ 13,952	$ 13,780
Real estate, fair value as a percentage of investments of consolidated funds	0.20%	0.30%
Real estate securities, cost	$ 23,160	$ 22,716
Investments, fair value that exceeds threshold | investment	0	0
Consolidated Funds | United States: | Communication services
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 148,272	$ 69,509
Debt securities, fair value as a percentage of investments of consolidated funds	2.60%	1.40%
Equity securities, fair value	$ 84,675	$ 79,522
Equity securities, fair value as a percentage of investments of consolidated funds	1.50%	1.50%
Consolidated Funds | United States: | Consumer discretionary
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 291,691	$ 202,355
Debt securities, fair value as a percentage of investments of consolidated funds	5.10%	3.90%
Equity securities, fair value	$ 40,063	$ 68,056
Equity securities, fair value as a percentage of investments of consolidated funds	0.70%	1.30%
Consolidated Funds | United States: | Consumer staples
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 54,040	$ 28,149
Debt securities, fair value as a percentage of investments of consolidated funds	0.90%	0.50%
Consolidated Funds | United States: | Energy
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 114,814	$ 110,990
Debt securities, fair value as a percentage of investments of consolidated funds	2.00%	2.20%
Equity securities, fair value	$ 430,082	$ 427,034
Equity securities, fair value as a percentage of investments of consolidated funds	7.50%	8.30%
Consolidated Funds | United States: | Financials
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 283,612	$ 223,794
Debt securities, fair value as a percentage of investments of consolidated funds	4.90%	4.40%
Equity securities, fair value	$ 234,302	$ 171,924
Equity securities, fair value as a percentage of investments of consolidated funds	4.10%	3.30%
Consolidated Funds | United States: | Health care
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 310,429	$ 226,554
Debt securities, fair value as a percentage of investments of consolidated funds	5.40%	4.40%
Equity securities, fair value	$ 33,294	$ 32,418
Equity securities, fair value as a percentage of investments of consolidated funds	0.60%	0.60%
Consolidated Funds | United States: | Industrials
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 462,602	$ 379,538
Debt securities, fair value as a percentage of investments of consolidated funds	8.00%	7.50%
Equity securities, fair value	$ 421,733	$ 369,019
Equity securities, fair value as a percentage of investments of consolidated funds	7.30%	7.20%
Consolidated Funds | United States: | Information technology
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 125,611	$ 87,355
Debt securities, fair value as a percentage of investments of consolidated funds	2.20%	1.70%
Equity securities, fair value	$ 43,997	$ 44,350
Equity securities, fair value as a percentage of investments of consolidated funds	0.80%	0.90%
Consolidated Funds | United States: | Materials
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 371,007	$ 333,459
Debt securities, fair value as a percentage of investments of consolidated funds	6.40%	6.50%
Consolidated Funds | United States: | Real estate
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 100,215	$ 97,621
Debt securities, fair value as a percentage of investments of consolidated funds	1.70%	1.90%
Real estate investments, at fair value	$ 13,952	$ 13,780
Real estate, fair value as a percentage of investments of consolidated funds	0.20%	0.30%
Consolidated Funds | United States: | Utilities
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 43,772	$ 19,954
Debt securities, fair value as a percentage of investments of consolidated funds	0.80%	0.40%
Equity securities, fair value	$ 70,118	$ 89,427
Equity securities, fair value as a percentage of investments of consolidated funds	1.20%	1.70%
Consolidated Funds | United States: | Other
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 514,516	$ 549,164
Debt securities, fair value as a percentage of investments of consolidated funds	8.90%	10.60%
Consolidated Funds | Europe:
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 266,920	$ 253,676
Debt securities, fair value as a percentage of investments of consolidated funds	4.50%	4.90%
Total debt securities, cost	$ 246,604	$ 231,315
Equity securities, fair value	$ 268,854	$ 264,564
Equity securities, fair value as a percentage of investments of consolidated funds	4.60%	5.10%
Total equity securities, cost	$ 207,847	$ 208,130
Real estate investments, at fair value	$ 172,729	$ 161,573
Real estate, fair value as a percentage of investments of consolidated funds	3.10%	3.10%
Real estate securities, cost	$ 171,035	$ 159,423
Consolidated Funds | Europe: | Communication services
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 103,870	$ 111,898
Debt securities, fair value as a percentage of investments of consolidated funds	1.80%	2.10%
Consolidated Funds | Europe: | Consumer discretionary
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 27,120	$ 18,560
Debt securities, fair value as a percentage of investments of consolidated funds	0.50%	0.40%
Equity securities, fair value	$ 53,933	$ 52,468
Equity securities, fair value as a percentage of investments of consolidated funds	0.90%	1.00%
Real estate investments, at fair value	$ 60,800	$ 61,357
Real estate, fair value as a percentage of investments of consolidated funds	1.10%	1.20%
Consolidated Funds | Europe: | Consumer staples
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 8,379	$ 3,107
Debt securities, fair value as a percentage of investments of consolidated funds	0.10%	0.10%
Consolidated Funds | Europe: | Energy
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 5,231	$ 1,185
Debt securities, fair value as a percentage of investments of consolidated funds	0.10%	0.00%
Consolidated Funds | Europe: | Financials
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 23,151	$ 18,381
Debt securities, fair value as a percentage of investments of consolidated funds	0.40%	0.40%
Equity securities, fair value	$ 48,808	$ 49,496
Equity securities, fair value as a percentage of investments of consolidated funds	0.80%	1.00%
Consolidated Funds | Europe: | Health care
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 11,760	$ 12,136
Debt securities, fair value as a percentage of investments of consolidated funds	0.20%	0.20%
Equity securities, fair value	$ 122	$ 19
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	$ 18,965	$ 15,993
Debt securities, fair value as a percentage of investments of consolidated funds	0.30%	0.30%
Equity securities, fair value	$ 101,724	$ 93,662
Equity securities, fair value as a percentage of investments of consolidated funds	1.80%	1.70%
Consolidated Funds | Europe: | Information technology
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 6,141	$ 5,402
Debt securities, fair value as a percentage of investments of consolidated funds	0.10%	0.10%
Consolidated Funds | Europe: | Materials
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 11,734	$ 13,487
Debt securities, fair value as a percentage of investments of consolidated funds	0.20%	0.30%
Equity securities, fair value	$ 24,282	$ 24,282
Equity securities, fair value as a percentage of investments of consolidated funds	0.40%	0.50%
Consolidated Funds | Europe: | Real estate
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 14,339	$ 13,424
Debt securities, fair value as a percentage of investments of consolidated funds	0.20%	0.30%
Equity securities, fair value	$ 39,985	$ 44,637
Equity securities, fair value as a percentage of investments of consolidated funds	0.70%	0.90%
Real estate investments, at fair value	$ 111,929	$ 100,216
Real estate, fair value as a percentage of investments of consolidated funds	2.00%	1.90%
Consolidated Funds | Europe: | Utilities
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 1,241	$ 5,417
Debt securities, fair value as a percentage of investments of consolidated funds	0.00%	0.10%
Consolidated Funds | Europe: | Other
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 34,989	$ 34,686
Debt securities, fair value as a percentage of investments of consolidated funds	0.60%	0.60%
Consolidated Funds | Asia and other:
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 758,894	$ 740,440
Debt securities, fair value as a percentage of investments of consolidated funds	13.10%	14.50%
Total debt securities, cost	$ 773,093	$ 761,394
Equity securities, fair value	$ 111,582	$ 99,452
Equity securities, fair value as a percentage of investments of consolidated funds	1.90%	1.90%
Total equity securities, cost	$ 101,880	$ 90,638
Consolidated Funds | Asia and other: | Communication services
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 509	$ 803
Debt securities, fair value as a percentage of investments of consolidated funds	0.00%	0.00%
Consolidated Funds | Asia and other: | Consumer discretionary
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 25,428	$ 17,195
Debt securities, fair value as a percentage of investments of consolidated funds	0.40%	0.30%
Consolidated Funds | Asia and other: | Consumer staples
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 19,999	$ 19,820
Debt securities, fair value as a percentage of investments of consolidated funds	0.30%	0.40%
Consolidated Funds | Asia and other: | Energy
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 2,381	$ 1,307
Debt securities, fair value as a percentage of investments of consolidated funds	0.00%	0.00%
Consolidated Funds | Asia and other: | Financials
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 8,094	$ 8,192
Debt securities, fair value as a percentage of investments of consolidated funds	0.10%	0.20%
Consolidated Funds | Asia and other: | Health care
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 400	$ 402
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	$ 5,127	$ 4,181
Debt securities, fair value as a percentage of investments of consolidated funds	0.10%	0.10%
Equity securities, fair value	$ 76,960	$ 63,161
Equity securities, fair value as a percentage of investments of consolidated funds	1.30%	1.20%
Consolidated Funds | Asia and other: | Information technology
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 46	$ 5
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	$ 282,392	$ 249,492
Debt securities, fair value as a percentage of investments of consolidated funds	5.00%	4.90%
Consolidated Funds | Asia and other: | Real estate
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 414,490	$ 435,799
Debt securities, fair value as a percentage of investments of consolidated funds	7.20%	8.50%
Equity securities, fair value	$ 32,916	$ 32,916
Equity securities, fair value as a percentage of investments of consolidated funds	0.60%	0.60%
Consolidated Funds | Asia and other: | Utilities
Schedule Of Investments In Marketable Securities [Line Items]
Debt securities, fair value	$ 28	$ 3,244
Debt securities, fair value as a percentage of investments of consolidated funds	0.00%	0.10%
Equity securities, fair value	$ 1,706	$ 3,375
Equity securities, fair value as a percentage of investments of consolidated funds	0.00%	0.10%