Mortgage Revenue Bonds - Schedule of MRBs Acquisitions (Parenthetical) (Details) - USD ($)	Sep. 30, 2021	Sep. 30, 2020
Schedule Of Available For Sale Securities [Line Items]
Commitment to provide maximum funding of MRB	$ 6,900,000
Maximum balance of the MRB after stabilization	$ 4,800,000
Mortgage Revenue Bonds [Member] | Ocotillo Springs [Member] | Brawley, CA [Member]
Schedule Of Available For Sale Securities [Line Items]
Maximum amount committed to fund		$ 15,000,000.0
Maximum balance of mortgage revenue bonds after stabilization		$ 3,500,000
Mortgage Revenue Bonds [Member] | Ocotillo Springs [Member] | Brawley, CA [Member] | LIBOR [Member]
Schedule Of Available For Sale Securities [Line Items]
Variable interest rate		3.25%
Floor rate		4.55%
Fixed interest rate		4.35%