COMMITMENTS AND CONTINGENCIES (Details)	1 Months Ended	3 Months Ended		6 Months Ended
	Jul. 31, 2020	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Aug. 04, 2020 USD ($)	Jun. 15, 2020 ft²	Dec. 31, 2019 USD ($)	Jun. 13, 2018
Loss Contingencies [Line Items]
Real estate redevelopment in process		$ 94,700,000		$ 94,700,000
Estimated cost to complete development and redevelopment projects		55,800,000		55,800,000
Delayed construction		300,000,000		300,000,000
Insurance coverage, general liability insurance, limit per occurrence		200,000,000		200,000,000
Insurance coverage, rental value insurance, limit per occurrence		500,000,000		500,000,000
Insurance coverage, pollution insurance, limit per occurence		50,000,000		50,000,000
Rental revenue deemed uncollectible				(13,079,000)	$ (773,000)
Deferred lease expense		$ 1,000,000.0		$ 1,000,000.0				$ 2,700,000
Puerto Rico
Loss Contingencies [Line Items]
Number of malls		2		2
Puerto Rico | Hurricane Maria
Loss Contingencies [Line Items]
Insurance coverage, rental value insurance, limit per occurrence		$ 147,000,000		$ 147,000,000
Shopping Center Wilkes-Barre, PA | Tornado | Hurricane Maria
Loss Contingencies [Line Items]
Casualty Gains (Losses)			$ 4,800,000
Gain on Business Interruption Insurance Recovery			200,000		300,000
Percentage of Rentable Area Damaged									13.00%
Proceeds from Insurance Settlement, Operating Activities			5,500,000
COVID-19
Loss Contingencies [Line Items]
Rental revenue deemed uncollectible		$ (12,500,000)		(13,900,000)
Rents received, percent		72.00%
Allowance for credit loss, writeoff		$ 6,000,000.0
COVID-19 | Paramus, NJ
Loss Contingencies [Line Items]
Rental revenue deemed uncollectible		(800,000)
Area of real estate property (in sq ft) | ft²							54,000
Annual Gross Rents				3,100,000
Allowance for credit loss, writeoff		$ 3,500,000		3,500,000
Loans And Leases Receivable, Gain (Loss) On Operating Lease				$ 800,000
COVID-19 | Subsequent Event
Loss Contingencies [Line Items]
Leasable area, gross, percent						94.00%
Rents received, percent	73.00%
Rent deferrals granted, amount						$ 700,000
Abatements granted, aggregate amount						$ 100,000
Annualized base rent tenants, percentage requesting rent relief						49.00%
Business Interruption [Member] | Hurricane [Member] | Puerto Rico | Hurricane Maria
Loss Contingencies [Line Items]
Insurance Settlements Receivable			14,300,000		14,300,000
Loss Contingency, Receivable, Proceeds					3,300,000
Loss Contingency, Insurance Deductible					$ 2,300,000
Gains (Losses) on Business Interruption			$ 8,700,000