RELATED PARTY TRANSACTIONS - Administration , Coinvestment and STRS JV (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Related Party Transaction [Line Items]
Administrative service fees	$ 171		$ 171	$ 512	$ 512
Net realized gains (losses)		$ 562		$ (15,537)	7,714
Administration Agreement
Related Party Transaction [Line Items]
Agreement may be terminated by either party without penalty upon days				60 days
Administrative service fees	171		171	$ 512	512
Administration Agreement | White Horse Advisers
Related Party Transaction [Line Items]
Affiliated funds invested	4,388,279	$ 4,502,807		4,388,279
Administration Agreement | STRS JV
Related Party Transaction [Line Items]
Proceeds from sale of investments	0		45,729	100,415	106,423
Net realized gains (losses)	$ 0		$ 120	$ 65	$ 277