Selected Quarterly Financial Data (Unaudited) - Schedule of Selected Quarterly Financial Data (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
SEC Schedule III, Real Estate and Accumulated Depreciation Disclosure [Abstract]
Total Income	$ 28,696,585	$ 28,684,937	$ 28,817,848	$ 26,448,549	$ 25,143,697	$ 25,355,051	$ 25,210,707	$ 23,504,374	$ 112,647,919	$ 99,213,829	$ 81,516,671
Total Expenses	24,567,878	24,704,729	24,858,243	22,485,487	20,634,766	21,567,389	21,176,977	19,876,382	96,616,337	83,255,514	72,076,546
Other Income (Expense)	(546,701)	(699,309)	(383,472)	(1,653,136)	(1,153,663)	(587,077)	(937,242)	(1,743,611)	(3,282,618)	(4,421,593)	(7,215,652)
Net Income	3,530,616	3,262,001	3,589,871	2,285,546	3,376,615	3,200,013	3,051,462	1,906,469	12,668,034	11,534,559	2,144,205
Net Loss Attributable to Common Shareholders	$ (795,765)	$ (5,179,423)	$ (199,876)	$ (1,504,201)	$ (413,132)	$ (589,734)	$ (682,729)	$ (883,278)	$ (7,679,265)	$ (2,568,873)	$ (6,122,993)
Net Loss Attributable to Common Shareholders Per Share - Basic and Diluted	$ (0.03)	$ (0.15)	$ (0.01)	$ (0.05)	$ (0.02)	$ (0.02)	$ (0.03)	$ (0.03)	$ (0.24)	$ (0.10)	$ (0.24)