Investment Portfolio - Summary of Partnership Investments (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Total Assets	$ 104,763,018	$ 113,050,560	$ 118,989,180
Variable Interest Entity, Nonconsolidated, Total Liabilities	24,622,223	21,779,556	25,217,600
Variable Interest Entity, Nonconsolidated, Total Assets and Liabilities, Net	80,140,795	91,271,004	93,771,580
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0	0	1,133
Variable Interest Entity, Nonconsolidated, Operating Income or Loss	(9,145,162)	8,346,265	23,358,257
Variable Interest Entity, Measure of Activity, Operating Income or Loss	0	0	1,798
Equity Method Investee [Member]
Variable Interest Entity [Line Items]
Equity Method Investment, Summarized Financial Information, Assets	11,653,249	15,131,651	3,117,223
Equity Method Investment, Summarized Financial Information, Liabilities	25,996	3,015	0
Equity Method Investment Summarized Financial Information, Equity	11,627,253	15,128,636	3,117,223
Equity Method Investments	11,274,109	14,652,589	3,000,328
Equity Method Investment, Summarized Financial Information, Net Income (Loss)	127,703	524,153	936,238
Income (Loss) from Equity Method Investments	$ 124,825	$ 491,951	$ 898,160