TENANT ORIGINATION AND ABSORPTION COSTS, ABOVE-MARKET LEASE ASSETS AND BELOW-MARKET LEASE LIABILITIES - Cost 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	$ 28,778		$ 28,778		$ 30,569
Tenant Origination and Absorption Costs, Accumulated Amortization	(11,507)		(11,507)		(10,223)
Tenant Origination and Absorption Costs, Net Amount	17,271		17,271		20,346
Tenant Origination and Absorption Costs, Amortization	(1,604)	$ (1,720)	(3,340)	$ (3,324)
Above-Market Lease Assets, Cost	3,499		3,499		3,714
Above-Market Lease Assets, Accumulated Amortization	(692)		(692)		(741)
Above-Market Lease Assets, Net Amount	2,807		2,807		2,973
Above-Market Lease Assets, Amortization	(74)	(101)	(166)	(202)
Below-Market Lease Liabilities, Cost	(4,322)		(4,322)		(4,958)
Below-Market Lease Liabilities, Accumulated Amortization	1,624		1,624		1,778
Below-Market Lease Liabilities, Net Amount	(2,698)		(2,698)		$ (3,180)
Below-Market Lease Liabilities, Amortization	$ 213	$ 385	$ 482	$ 738