TENANT ORIGINATION AND ABSORPTION COSTS, ABOVE-MARKET LEASE ASSETS AND BELOW-MARKET LEASE LIABILITIES - Net Amount and Amortization (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Tenant Origination and Absorption Costs, Above-Market Lease Assets and Below-Market Lease Liabilities [Abstract]
Tenant Origination And Absorption Costs, Cost	$ 13,425		$ 13,425		$ 15,422
Tenant Origination and Absorption Costs, Accumulated Amortization	(7,349)		(7,349)		(7,954)
Tenant Origination and Absorption Costs, Net Amount	6,076		6,076		7,468
Tenant Origination and Absorption Costs, Amortization expense	(673)	$ (888)	(1,393)	$ (1,831)
Above-Market Lease Assets, Cost	72		72		72
Above-Market Lease Assets, Accumulated Amortization	(34)		(34)		(28)
Above-Market Lease Assets, Net Amount	38		38		44
Above-Market Lease Assets, Amortization expense	(3)	(4)	(6)	(9)
Below-Market Lease Liabilities, Cost	(8,962)		(8,962)		(10,802)
Below-Market Lease Liabilities, Accumulated Amortization	5,299		5,299		6,125
Below-Market Lease Liabilities, Net Amount	(3,663)		(3,663)		$ (4,677)
Below-Market Lease Liabilities, Amortization expense	$ 472	$ 679	$ 1,014	$ 1,382