REAL ESTATE ASSETS (2020 and 2019 Impairment) (Details) ft² in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($) ft² property	Mar. 31, 2019 USD ($) ft² property
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of properties impaired | property	7	7
Area of real estate property impaired (sq ft) | ft²	414	1,100
Impairment of real estate assets	$ 11,676	$ 20,073
Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Real estate asset deemed to be impaired	64,300	139,000
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	$ 52,600	$ 118,900