ACQUISITIONS AND DISPOSITIONS (Narrative, Dispositions) (Details) $ in Thousands										3 Months Ended	12 Months Ended
	Dec. 18, 2020 USD ($)	Nov. 20, 2020 USD ($) a	Jul. 16, 2020 USD ($) hotel_room	Jun. 29, 2020 USD ($)	Mar. 13, 2020 USD ($) a ft² parking_spaces	Dec. 30, 2019 USD ($)	Dec. 20, 2019 USD ($)	Oct. 29, 2019 USD ($) a	Sep. 16, 2019 USD ($) a ft²	Mar. 31, 2020 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 17, 2020	Jul. 15, 2020	Nov. 30, 2019 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Equity in earnings (losses) from real estate and other affiliates											$ 271,099	$ 30,629	$ 39,954
Proceeds from sales of properties											24,373	67,110	0
Carrying value of the asset											6,685,069	6,760,355
Gain (loss) on sale or disposal of real estate and other assets, net											59,942	22,362	(4)
Selling profit from sales-type leases											0	13,537
Net investment in lease receivable											2,926	79,166
Payments to acquire real estate						$ 584,300
Proceeds from the sale of lease receivable											64,155	0	0
Pre-tax net loss since the acquisition date											8,480	103,540	73,218
Equity Method Investments
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Carrying value of equity method investments											373,192	117,804
Equity in earnings (losses) from real estate and other affiliates											267,375	27,006	$ 36,599
Elk Grove
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of land sold | a		64
Proceeds from sales of properties		$ 24,600
Carrying value of the asset		10,800
Gain (loss) on sale or disposal of real estate and other assets, net		$ 13,700
West Windsor
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of land sold | a								658
Gain (loss) on sale or disposal of real estate and other assets, net				$ 8,000				$ 12,000
Assets divested from deconsolidation								27,500
Proceeds from sale								$ 40,000
100 Fellowship Drive
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of land sold | a					13.5
Proceeds from sales of properties					$ 115,000
Gain (loss) on sale or disposal of real estate and other assets, net										$ 38,300
Area of real estate property sold | ft²					203,257
Number of parking spaces | parking_spaces					550
Selling profit from sales-type leases												$ 13,500
Amount derecognized from Developments for sales-type leases																$ 63,700
Net investment in lease receivable					$ 76,100											$ 75,900
Transaction costs on sales of investments real estate					200
Payments to acquire real estate					$ 600
Proceeds from the sale of lease receivable											$ 64,200
Cottonwood Mall
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sales of properties									$ 10,000
Gain (loss) on sale or disposal of real estate and other assets, net									24,100
Assets divested from deconsolidation									21,500
Proceeds from sale									$ 46,000
Square footage of building | ft²									196,975
Note receivable									$ 36,000
Land Parcel in Holladay, Utah
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of land sold | a									54
Circle T
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Equity method investment, ownership percentage														50.00%
Proceeds from sale of equity method investments	$ 13,000
Carrying value of equity method investments	11,900
Equity in earnings (losses) from real estate and other affiliates	$ 1,100
Mr.C Seaport
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Equity method investment, ownership percentage															35.00%
Proceeds from sale of equity method investments			$ 800
Mr.C Seaport | Equity Method Investments
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of hotel rooms | hotel_room			66
Bridges at Mint Hill
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Equity method investment, ownership percentage							90.50%
Equity in earnings (losses) from real estate and other affiliates							$ 9,500
Gain (loss) on sale or disposal of real estate and other assets, net							(8,800)
Assets divested from deconsolidation							22,000
Pre-tax net loss since the acquisition date							$ 3,800