SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of fair value measurement of level 3 financial assets and liabilities (Details) - Significant unobservable inputs (Level 3) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Equity securities
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance at beginning of period	$ 359,041	$ 388,664	$ 368,465	$ 377,549
Fair Value Adjustments	17,287	(19,504)	8,271	(24,047)
Relating to Undistributed Earnings	12	0	12	0
Purchases, Sales and Settlements	10,918	(1,489)	17,405	18,423
Transfer in and/or out of Level 3	(128)	(33,755)	(7,023)	(38,009)
Balance at end of period	387,130	333,916	387,130	333,916
Equity securities | Trading income (loss) and fair value adjustments
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Fair Value Adjustments	13,932		13,920
Equity securities | Realized and unrealized gains (losses) on investments
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Fair Value Adjustments	3,355		(5,649)
Loans receivable at fair value
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance at beginning of period	772,085	882,391	701,652	873,186
Fair Value Adjustments	9,207	(10,984)	52,666	(47)
Relating to Undistributed Earnings	(1,281)	2,135	(1,050)	5,373
Purchases, Sales and Settlements	(95,934)	(61,865)	(69,191)	(66,835)
Transfer in and/or out of Level 3	(250)	(40,837)	(250)	(40,837)
Balance at end of period	683,827	770,840	683,827	770,840
Mandatorily redeemable noncontrolling interests issued after November 5, 2003
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance at beginning of period	4,654	4,502	4,648	4,506
Fair Value Adjustments	0	0	0	0
Relating to Undistributed Earnings	470	221	778	468
Purchases, Sales and Settlements	(772)	(563)	(1,074)	(814)
Transfer in and/or out of Level 3	0	0	0	0
Balance at end of period	4,352	4,160	4,352	4,160
Contingent consideration
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance at beginning of period	28,884	22,464	31,046	0
Fair Value Adjustments	(1,123)	(4,500)	(4,570)	(4,500)
Relating to Undistributed Earnings	0	0	0	0
Purchases, Sales and Settlements	(37)	(242)	1,248	22,222
Transfer in and/or out of Level 3	0	0	0	0
Balance at end of period	$ 27,724	$ 17,722	$ 27,724	$ 17,722