Mortgage Revenue Bonds - Schedule of Investments in MRBs (Parenthetical) (Details) - USD ($)	Mar. 31, 2022	Dec. 31, 2021
Schedule Of Available For Sale Securities [Line Items]
Remaining partnership commitment fund amount	$ 276,325,887
Mortgage Revenue Bonds Held In Trust [Member]
Schedule Of Available For Sale Securities [Line Items]
Partnership funded amount	648,919,774	$ 639,116,502
Mortgage Revenue Bond [Member] | Meadow Valley [Member]
Schedule Of Available For Sale Securities [Line Items]
Commitment to provide maximum funding of MRB	44,000,000.0
Partnership funded amount	100,000
Remaining partnership commitment fund amount	$ 43,900,000