Schedule III - Real Estate and Accumulated Depreciation (Details 1) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Balance at January 1	$ 589,147,012	$ 476,168,824	$ 398,811,830
Construction and acquisition cost	196,672,924	143,365,974	82,692,554
Impairment charge	0	(3,020,000)	(450,000)
Disposition of real estate	(29,970,998)	(27,367,786)	(4,885,560)
Balance at December 31	$ 755,848,938	$ 589,147,012	$ 476,168,824