BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES - Variable Interest Entities and Marketable Securities (Details) - USD ($) $ in Thousands	3 Months Ended	20 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Payments for acquisition of noncontrolling interests – consolidated real estate entities	$ 12,200
Cost	4,264	$ 6,942
Gross Unrealized Gain (Loss)	$ (2,261)	113
71 France | Investors Real Estate Trust
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Ownership acquired	47.40%
Fair Value, Recurring | Fair Value, Inputs, Level 1
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Carrying Value	$ 2,003	$ 7,055