Equity (Details 3) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014
Accumulated Other Comprehensive Loss
Accumulated other comprehensive loss	$ 25,237,253		$ 14,668,250
Net unrealized losses on derivatives designated as cash flow hedges	26,300,000		15,000,000
Deferred losses on terminated interest swaps			1,100,000
Unrealized gain related to available-for-sale securities	1,100,000		300,000
Income attributable to noncontrolling interest	100,000	200,000
Distributions attributable to noncontrolling interest	2,055,972	217,922
Interest Expense
Accumulated Other Comprehensive Loss
Net realized losses on derivatives designated as cash flow hedges	(14,131,036)		(10,706,246)
Other Income
Accumulated Other Comprehensive Loss
Net realized gain on sale of available-for-sale investments	$ 100,000		$ 431,476