Real Estate and Accumulated Depreciation (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Investment in real estate:
Balance at beginning of year		$ 29,865,490	[1]	$ 25,491,935	[1]	$ 23,734,733
Additions:
Acquisitions		2,145,590		3,364,891		2,210,600
Improvements		672,008		445,625		380,298
Assumed other items, net		172,095		389,256		160,897
Assumed debt		63,732		1,064,810		265,152
Total additions		3,053,425		5,264,582		3,016,947
Deductions:
Cost of real estate sold		(2,118,305)		(449,932)		(916,997)
Reclassification of accumulated depreciation and amortization for assets held for sale		(292,914)		(41,464)		(64,476)
Impairment of assets		(37,207)		(2,220)		0
Total deductions		(2,448,426)		(493,616)		(981,473)
Foreign currency translation on real estate, net		(429,431)		(397,411)		(278,272)
Balance at end of year	[1]	30,041,058		29,865,490		25,491,935
Accumulated depreciation:
Balance at beginning of year		3,796,297		3,020,908		2,386,658
Additions:
Depreciation and amortization expenses		901,242		826,240		844,130
Amortization of above market leases		7,909		11,912		7,935
Total additions		909,151		838,152		852,065
Deductions:
Sale of properties		(221,737)		(69,735)		(123,582)
Reclassification of accumulated depreciation and amortization for assets held for sale		(292,914)		(41,464)		(64,476)
Total deductions		(514,651)		(111,199)		(188,058)
Foreign currency translation on accumulated depreciation, net		(97,303)		48,436		(29,757)
Balance at end of year		4,093,494	[2]	$ 3,796,297		$ 3,020,908
Reconciliation of real property (Textual) [Abstract]
Aggregate cost for tax purposes for real property		$ 24,887,189

[1] The unaudited aggregate cost for tax purposes for real property equals $24,887,189,000 at December 31, 2016.

[2] Please see Note 2 to our consolidated financial statements for information regarding lives used for depreciation and amortization.