TENANT ORIGINATION AND ABSORPTION COSTS, ABOVE-MARKET LEASE ASSETS AND BELOW-MARKET LEASE LIABILITIES (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 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	$ 84,330		$ 84,330		$ 95,808
Tenant Origination and Absorption Costs, Accumulated Amortization	(54,044)		(54,044)		(56,886)
Tenant Origination and Absorption Costs, Net Amount	30,286		30,286		38,922
Tenant Origination and Absorption Costs, Amortization expense	(2,409)	$ (3,766)	(7,702)	$ (18,185)
Above-Market Lease Assets, Cost	1,146		1,146		2,661
Above-Market Lease Assets, Accumulated Amortization	(671)		(671)		(2,095)
Above-Market Lease Assets, Net Amount	475		475		566
Above-Market Lease Assets, Amortization expense	(26)	(142)	(91)	(866)
Below-Market Lease Liabilities, Cost	(24,572)		(24,572)		(25,630)
Below-Market Lease Liabilities, Accumulated Amortization	16,951		16,951		15,781
Below-Market Lease Liabilities, Net Amount	(7,621)		(7,621)		$ (9,849)
Below-Market Lease Liabilities, Amortization expense	$ 726	$ 874	$ 2,228	$ 3,698