SCHEDULE III—REAL ESTATE AND ACCUMULATED DEPRECIATION (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Change in total cost of properties
Balance at beginning of year	$ 7,684,059	$ 7,090,078	$ 6,825,627
Acquisitions and capital expenditures	455,373	665,300	277,432
Dispositions	(31,261)	(71,319)	(12,981)
Balance at close of year	8,108,171	7,684,059	7,090,078
Change in accumulated depreciation
Balance at beginning of year	1,938,823	1,727,032	1,513,482
Depreciation expense	270,285	238,941	222,249
Dispositions	(31,261)	(27,150)	(8,699)
Balance at close of year	2,177,847	$ 1,938,823	$ 1,727,032
Tax basis for federal income tax purpose	$ 5,852,922