Variable Interest Entities - Variable Interest Entities Property Asset Carrying Value and Maximum Exposure (Details) - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Accounts Notes And Loans Receivable [Line Items]
Available for Sale Security and Property Loan Receivable, Maximum Exposure	$ 186,931,601	$ 201,777,735
Mortgage Revenue Bonds [Member]
Accounts Notes And Loans Receivable [Line Items]
Available for Sale Security and Property Loan Receivable, Maximum Exposure	118,447,248	146,344,195
Property Loan [Member]
Accounts Notes And Loans Receivable [Line Items]
Available for Sale Security and Property Loan Receivable, Maximum Exposure	15,674,613	15,824,613
Investment in Unconsolidated Entities [Member]
Accounts Notes And Loans Receivable [Line Items]
Available for Sale Security and Property Loan Receivable, Maximum Exposure	$ 52,809,740	$ 39,608,927