REAL ESTATE AND ACCUMULATED DEPRECIATION (Details 2) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) residential_condominium	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Estimated useful lives
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Federal Income Tax Basis	$ 22,969,235
Number of Residential Condominiums Sold | residential_condominium	70
Aggregate cost of total real estate for federal income tax purposes	$ 22,969,235
Changes in total real estate assets
Balance, beginning of period	23,606,872	$ 22,342,576	$ 21,935,936
Acquisitions, construction costs and improvements	860,594	1,615,949	1,568,878
Dispositions, including impairment loss on planned dispositions	(505,244)	(351,653)	(1,162,238)
Balance, end of period	23,962,222	23,606,872	22,342,576
Changes in accumulated depreciation
Balance, beginning of period	5,173,883	4,611,646	4,218,379
Depreciation, including discontinued operations	707,331	661,578	631,196
Dispositions	(152,774)	(99,341)	(237,929)
Balance, end of period	$ 5,728,440	$ 5,173,883	$ 4,611,646
Building
Estimated useful lives
Estimated useful lives of assets (in years)	30 years
Improvements, upgrades and FF&E
Estimated useful lives
Estimated useful lives of assets (in years)	7 years