INVESTMENTS IN REAL ESTATE AND OTHER SECURITIES - Summary of Activity Related to Credit Losses on Debt Securities (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2020 USD ($)
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses on available-for-sale debt securities at December 31, 2019	$ 0
Additions to the allowance for credit losses on securities for which credit losses were not previously recorded	0
Additions to the allowance for credit losses arising from purchases of available-for-sale debt securities accounted for as purchased financial assets with credit deterioration	0
Reductions for securities sold during the period	0
Reductions in the allowance for credit losses because the entity intends to sell the security or more likely than not will be required to sell the security before recovery of its amortized cost basis	0
Additional increases (decreases) to the allowance for credit losses on securities that had credit losses or an allowance recorded in a previous period	14,218
Write-offs charged against the allowance	0
Recoveries of amounts previously written off	0
Allowance for credit losses on available-for-sale debt securities at June 30, 2020	14,218
Purchased Credit Deteriorated
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses on available-for-sale debt securities at December 31, 2019	0
Additions to the allowance for credit losses on securities for which credit losses were not previously recorded	0
Additions to the allowance for credit losses arising from purchases of available-for-sale debt securities accounted for as purchased financial assets with credit deterioration	0
Reductions for securities sold during the period	0
Reductions in the allowance for credit losses because the entity intends to sell the security or more likely than not will be required to sell the security before recovery of its amortized cost basis	0
Additional increases (decreases) to the allowance for credit losses on securities that had credit losses or an allowance recorded in a previous period	13,808
Write-offs charged against the allowance	0
Recoveries of amounts previously written off	0
Allowance for credit losses on available-for-sale debt securities at June 30, 2020	13,808
Non-Purchased Credit Deteriorated
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses on available-for-sale debt securities at December 31, 2019	0
Additions to the allowance for credit losses on securities for which credit losses were not previously recorded	0
Additions to the allowance for credit losses arising from purchases of available-for-sale debt securities accounted for as purchased financial assets with credit deterioration	0
Reductions for securities sold during the period	0
Reductions in the allowance for credit losses because the entity intends to sell the security or more likely than not will be required to sell the security before recovery of its amortized cost basis	0
Additional increases (decreases) to the allowance for credit losses on securities that had credit losses or an allowance recorded in a previous period	410
Write-offs charged against the allowance	0
Recoveries of amounts previously written off	0
Allowance for credit losses on available-for-sale debt securities at June 30, 2020	$ 410