TENANT ORIGINATION AND ABSORPTION COSTS, ABOVE-MARKET LEASE ASSETS AND BELOW-MARKET LEASE LIABILITIES - Cost and Amortization (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 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	$ 30,179		$ 30,569
Tenant Origination and Absorption Costs, Accumulated Amortization	(11,567)		(10,223)
Tenant Origination and Absorption Costs, Net Amount	18,612		20,346
Tenant Origination and Absorption Costs, Amortization	(1,736)	$ (1,604)
Above-Market Lease Assets, Cost	3,714		3,714
Above-Market Lease Assets, Accumulated Amortization	(833)		(741)
Above-Market Lease Assets, Net Amount	2,881		2,973
Above-Market Lease Assets, Amortization	(92)	(101)
Below-Market Lease Liabilities, Cost	(4,810)		(4,958)
Below-Market Lease Liabilities, Accumulated Amortization	1,899		1,778
Below-Market Lease Liabilities, Net Amount	(2,911)		$ (3,180)
Below-Market Lease Liabilities, Amortization	$ 269	$ 353