Schedule III - Real Estate and Accumulated Depreciation (Details) - Changes in Total Real Estate Assets and Accumulated Depreciation - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Changes in Total Real Estate Assets and Accumulated Depreciation [Abstract]
Balance, beginning of period	$ 10,018,225,775	$ 9,123,343,869	$ 8,947,286,646
Balance, end of period	11,568,809,126	10,018,225,775	9,123,343,869
Balance, beginning of period	1,955,405,720	1,878,680,836	1,745,461,577
Balance, end of period	2,115,319,888	1,955,405,720	1,878,680,836
Acquisitions	278,401,182	548,553,619	475,108,219
Improvements	191,662,698	134,921,993	107,411,806
Transfers from (to) unconsolidated joint ventures	1,673,542,610	1,065,330,540	317,995,154
Sales	(507,185,370)	(781,200,981)	(559,328,593)
Assets held for sale	(587,007)		(77,664,078)
Adjustment of fully depreciated asset	(56,774,522)	(8,628,954)	(4,780,841)
Adjustment of property carrying values	(18,432,226)	(32,935,408)	(69,463,649)
Change in exchange rate	(10,044,014)	(31,158,903)	(13,220,795)
Depreciation for year	333,948,605	256,088,382	243,011,431
Sales	(116,864,875)	(167,458,882)	(96,915,316)
Adjustment of fully depreciated asset	(56,774,522)	(8,628,954)	(4,780,841)
Assets held for sale			(7,351,096)
Change in exchange rate	$ (395,040)	$ (3,275,662)	$ (744,919)