FAIR VALUE MEASUREMENT - Purchase Option Value (Details) $ in Thousands	Mar. 31, 2021 USD ($)
Real Estate Loan 1
Purchase Option Roll Forward [Roll Forward]
Purchase Option Value, beginning balance	$ 1,600
Purchase Option Value, ending balance	1,600
Real Estate Loan 2
Purchase Option Roll Forward [Roll Forward]
Purchase Option Value, beginning balance	2,761
Purchase Option Value, ending balance	2,761
Real Estate Loan 3
Purchase Option Roll Forward [Roll Forward]
Purchase Option Value, beginning balance	2,800
Purchase Option Value, ending balance	$ 2,800