| FAIR VALUE MEASUREMENTS (Tables)
 | 12 Months Ended | 
| Dec. 31, 2022 | 
|---|
| Fair Value Disclosures [Abstract] |  | 
| Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis | The following table presents assets that are measured at fair value on a recurring basis as of December 31, 2022 and 2021 (in thousands): 
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
|  | Level 1 |  | Level 2 |  | Level 3 |  | Measured at NAV
 |  | Total |  
| December 31, 2022 |  |  |  |  |  |  |  |  |  |  
| Assets: |  |  |  |  |  |  |  |  |  |  
| Common shares in publicly traded company | $ | 86 |  |  | $ | — |  |  | $ | — |  |  | $ | — |  |  | $ | 86 |  |  
| Exchange traded funds | 2,117 |  |  | — |  |  | — |  |  | — |  |  | 2,117 |  |  
| Mutual funds | 12,411 |  |  | — |  |  | — |  |  | — |  |  | 12,411 |  |  
| Accrued performance allocations | — |  |  | — |  |  | — |  |  | 554,723 |  |  | 554,723 |  |  
| Partnership interests | — |  |  | — |  |  | — |  |  | 77,087 |  |  | 77,087 |  |  
| Other investments | — |  |  | — |  |  | 8,369 |  |  | — |  |  | 8,369 |  |  
| Total assets at fair value | $ | 14,614 |  |  | $ | — |  |  | $ | 8,369 |  |  | $ | 631,810 |  |  | $ | 654,793 |  |  
|  |  |  |  |  |  |  |  |  |  |  
| Liabilities: |  |  |  |  |  |  |  |  |  |  
| General Partner Notes Payable | $ | — |  |  | $ | — |  |  | $ | — |  |  | $ | 8,633 |  |  | $ | 8,633 |  |  
|  |  |  |  |  |  |  |  |  |  |  
| December 31, 2021 |  |  |  |  |  |  |  |  |  |  
| Assets: |  |  |  |  |  |  |  |  |  |  
| Exchange traded funds | $ | 1,171 |  |  | $ | — |  |  | $ | — |  |  | $ | — |  |  | $ | 1,171 |  |  
| Mutual funds | 6,864 |  |  | — |  |  | — |  |  | — |  |  | 6,864 |  |  
| Accrued performance allocations | — |  |  | — |  |  | — |  |  | 439,548 |  |  | 439,548 |  |  
| Partnership interests | — |  |  | — |  |  | — |  |  | 39,685 |  |  | 39,685 |  |  
| Other investments | — |  |  | — |  |  | 4,321 |  |  | — |  |  | 4,321 |  |  
| Total assets at fair value | $ | 8,035 |  |  | $ | — |  |  | $ | 4,321 |  |  | $ | 479,233 |  |  | $ | 491,589 |  |  
|  |  |  |  |  |  |  |  |  |  |  
| Liabilities: |  |  |  |  |  |  |  |  |  |  
| General Partner Notes Payable | $ | — |  |  | $ | — |  |  | $ | — |  |  | $ | 12,003 |  |  | $ | 12,003 |  |  | 
| Summary of Changes in Fair Value of Company's Level 3 Assets | The following table presents a rollforward of Level 3 assets at cost adjusted for any impairment and observable price changes (in thousands): 
|  |  |  |  |  |  |  
|  | Other Investments
 |  
| Balance as of December 31, 2020 | $ | 345 |  |  
| Purchases | 1,141 |  |  
| Net unrealized gains | 2,835 |  |  
| Balance as of December 31, 2021 | $ | 4,321 |  |  
| Purchases | 4,048 |  |  
| Balance as of December 31, 2022 | $ | 8,369 |  |  | 
| Summary of Investments Valued Using NAV | The following table presents investments carried at fair value using NAV (in thousands): 
|  |  |  |  |  |  |  |  |  |  |  |  |  
|  | Fair Value |  | Unfunded Commitments
 |  
| December 31, 2022: |  |  |  |  
| Accrued performance allocations | $ | 554,723 |  |  | $ | — |  |  
|  |  |  |  |  
| Partnership interests: |  |  |  |  
| Company-sponsored open-end fund | 26,169 |  |  | 20,755 |  |  
| Company-sponsored closed-end funds | 39,120 |  |  | 3,763 |  |  
| Third-party closed-end funds | 11,798 |  |  | 5,569 |  |  
| Total partnership interests | $ | 77,087 |  |  | $ | 30,087 |  |  
|  |  |  |  |  
| December 31, 2021: |  |  |  |  
| Accrued performance allocations | $ | 439,548 |  |  | $ | — |  |  
|  |  |  |  |  
| Partnership interests: |  |  |  |  
| Company-sponsored open-end fund | 15,474 |  |  | — |  |  
| Company-sponsored closed-end funds | 16,510 |  |  | 20,885 |  |  
| Third-party closed-end funds | 7,701 |  |  | 2,436 |  |  
| Total partnership interests | $ | 39,685 |  |  | $ | 23,321 |  |  | 
| Summary of Carrying Amounts and Estimated Fair Values of Financial Instruments at Amortized Cost | The following table presents the carrying amounts and estimated fair values of financial instruments reported at amortized cost (in thousands): 
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
|  | Level 1 |  | Level 2 |  | Level 3 |  | Total |  | Carrying Value
 |  
| As of December 31, 2022: |  |  |  |  |  |  |  |  |  |  
| Notes payable (private notes) | $ | — |  |  | $ | — |  |  | $ | 270,270 |  |  | $ | 270,270 |  |  | $ | 300,000 |  |  
|  |  |  |  |  |  |  |  |  |  |  
| As of December 31, 2021: |  |  |  |  |  |  |  |  |  |  
| Notes payable (private notes) | $ | — |  |  | $ | — |  |  | $ | 144,577 |  |  | $ | 144,577 |  |  | $ | 150,000 |  |  |