REAL ESTATE AND ACCUMULATED DEPRECIATION (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Estimated useful lives
Aggregate cost of total real estate for federal income tax purposes	$ 18,958
Changes in total real estate assets
Balance, beginning of period	17,849,316	$ 16,800,321	$ 10,071,342
Acquisitions, construction costs and improvements	1,667,989	1,311,003	7,157,639
Dispositions, including impairment loss on planned dispositions	(249,206)	(262,008)	(428,660)
Balance, end of period	19,268,099	17,849,316	16,800,321
Changes in accumulated depreciation
Balance, beginning of period	2,913,576	2,516,112	2,056,222
Depreciation, including discontinued operations	477,923	442,682	573,715
Dispositions	(65,709)	(45,218)	(113,825)
Balance, end of period	$ 3,325,790	$ 2,913,576	$ 2,516,112
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