REAL ESTATE ASSETS (Impairment) (Details) ft² in Thousands, $ in Thousands	9 Months Ended
	Sep. 30, 2020 USD ($) ft² property	Sep. 30, 2019 USD ($) ft² property
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of properties impaired | property	11	26
Area of real estate property impaired (sq ft) | ft²	699	2,600
Impairment of real estate assets	$ 15,983	$ 57,163
Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Real estate asset deemed to be impaired	87,500	340,300
Estimate of Fair Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Real estate asset deemed to be impaired	$ 71,500	$ 283,100