Investments in Mortgage Revenue Bonds - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Schedule Of Available For Sale Securities [Line Items]
Contingent interest income	$ 3,045,462	$ 9,322,849
Lake Forest [Member] | Daytona Florida [Member] | Mortgage Revenue Bonds [Member]
Schedule Of Available For Sale Securities [Line Items]
Contingent interest income	4,200,000
Lake Forest [Member] | Daytona Florida [Member] | Mortgage Revenue Bonds [Member] | Other Income [Member]
Schedule Of Available For Sale Securities [Line Items]
Gain on early redemption of mortgage revenue bonds	1,500,000
Vantage at Judson [Member] | San Antonio, TX [Member] | Mortgage Revenue Bonds [Member] | Series B [Member]
Schedule Of Available For Sale Securities [Line Items]
Gain on early redemption of mortgage revenue bonds	$ 2,200,000