SEGMENT INFORMATION - Select Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Segment Reporting Information [Line Items]
Net Revenue (Loss)	$ 795,997	$ 685,349	$ 1,444,048	$ 1,450,102
Adjusted Compensation and Benefits Expense	504,263	451,864	925,549	944,597
Adjusted Non-compensation Expense	157,371	148,612	305,253	282,905
Other Segment Items	(26,131)	(707)	(30,997)	(18,895)
Adjusted Operating Income (Loss)	108,232	84,166	182,249	203,705
Interest income (included in net revenue)	9,207	12,854	20,869	24,325
Depreciation and amortization of property (included in adjusted non-compensation expense)	8,613	9,204	17,044	18,293
Financial Advisory
Segment Reporting Information [Line Items]
Net Revenue (Loss)	497,306	411,308	864,665	864,815
Adjusted Compensation and Benefits Expense	317,036	275,324	557,004	577,404
Adjusted Non-compensation Expense	52,426	51,112	104,987	98,977
Other Segment Items	(5,947)	(3,372)	(3,763)	(10,245)
Adjusted Operating Income (Loss)	121,897	81,500	198,911	178,189
Interest income (included in net revenue)	1,903	1,310	3,100	2,276
Depreciation and amortization of property (included in adjusted non-compensation expense)	2,165	2,166	4,175	4,415
Asset Management
Segment Reporting Information [Line Items]
Net Revenue (Loss)	292,478	285,487	580,578	580,963
Adjusted Compensation and Benefits Expense	139,655	134,318	282,482	285,016
Adjusted Non-compensation Expense	63,597	55,687	122,808	111,262
Other Segment Items	(23,987)	(20,268)	(47,593)	(39,810)
Adjusted Operating Income (Loss)	65,239	75,214	127,695	144,875
Interest income (included in net revenue)	2,136	3,809	4,583	7,520
Depreciation and amortization of property (included in adjusted non-compensation expense)	1,407	1,392	2,788	2,681
Corporate
Segment Reporting Information [Line Items]
Net Revenue (Loss)	6,213	(11,446)	(1,195)	4,324
Adjusted Compensation and Benefits Expense	47,572	42,222	86,063	82,177
Adjusted Non-compensation Expense	41,348	41,813	77,458	72,666
Other Segment Items	3,803	22,933	20,359	31,160
Adjusted Operating Income (Loss)	(78,904)	(72,548)	(144,357)	(119,359)
Interest income (included in net revenue)	5,168	7,735	13,186	14,529
Depreciation and amortization of property (included in adjusted non-compensation expense)	$ 5,041	$ 5,646	$ 10,081	$ 11,197