OTHER ASSETS AND LIABILITIES, GENERAL AND ADMINISTRATIVE, AND OTHER ITEMS - Schedule of Notes and Loans Receivable (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2021 USD ($)
Financing Receivable [Roll Forward]
Beginning balance	$ 52,389
Fundings	251,689
Accrued interest payment-in-kind	2,736
Proceeds from repayments	0
Fair value adjustment, changes in instrument-specific credit risk	0
Fair value adjustment, other factors	(3,159)
Ending balance	303,655
Notes Receivable
Financing Receivable [Roll Forward]
Beginning balance	52,389
Fundings	1,689
Accrued interest payment-in-kind	2,736
Proceeds from repayments	0
Fair value adjustment, changes in instrument-specific credit risk	0
Fair value adjustment, other factors	(3,159)
Ending balance	53,655
Loans Receivable
Financing Receivable [Roll Forward]
Beginning balance	0
Fundings	250,000
Accrued interest payment-in-kind	0
Proceeds from repayments	0
Fair value adjustment, changes in instrument-specific credit risk	0
Fair value adjustment, other factors	0
Ending balance	$ 250,000