Variable Interest Entities - Variable Interest Entities Property Asset Carrying Value and Maximum Exposure (Details) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Accounts Notes And Loans Receivable [Line Items]
Available for Sale Security and Property Loan Receivable, Maximum Exposure	$ 162,177,260	$ 201,777,735
Mortgage Revenue Bonds [Member]
Accounts Notes And Loans Receivable [Line Items]
Available for Sale Security and Property Loan Receivable, Maximum Exposure	66,358,000	146,344,195
Property Loan [Member]
Accounts Notes And Loans Receivable [Line Items]
Available for Sale Security and Property Loan Receivable, Maximum Exposure	15,524,613	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	$ 80,294,647	$ 39,608,927