Mortgage Revenue Bonds - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	Jul. 31, 2021	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Schedule Of Available For Sale Securities [Line Items]
Provision for credit loss			$ 3,463,253	$ 900,080	$ 5,285,609
Redemption of contingent interest income	$ 1,800,000
Provision Center 2014-1 [Member]
Schedule Of Available For Sale Securities [Line Items]
Provision for credit loss		$ 0		$ 900,000
Live 929 Apartments [Member]
Schedule Of Available For Sale Securities [Line Items]
Provision for credit loss			$ 3,500,000
Live 929 Apartments and Provision Center 2014-1 [Member]
Schedule Of Available For Sale Securities [Line Items]
Provision for credit loss					$ 5,300,000
Rosewood Townhomes and South Pointe Apartments [Member] | Series A MRB [Member]
Schedule Of Available For Sale Securities [Line Items]
Redemption price	106.00%