Mortgage Revenue Bonds - Schedule of MRBs Acquisitions (Details)		12 Months Ended
		Dec. 31, 2020 USD ($) Unit	Dec. 31, 2019 USD ($) Unit
Schedule Of Available For Sale Securities [Line Items]
Units | Unit		3,756
Principal Acquired | $		$ 9,498,500	$ 19,250,000
Arby Road Apartments [Member] | Series A [Member] | Las Vegas, NV [Member]
Schedule Of Available For Sale Securities [Line Items]
Month Acquired	[1]	June
Units | Unit	[1]	180
Maturity Date	[1]	Oct. 01, 2027
Interest Rate	[1]	5.35%
Principal Acquired | $	[1]	$ 1,690,000
Arby Road Apartments [Member] | Series A [Member] | Las Vegas, NV [Member]
Schedule Of Available For Sale Securities [Line Items]
Month Acquired	[1]	June
Units | Unit	[1]	180
Maturity Date	[1]	Apr. 01, 2041
Interest Rate	[1]	5.50%
Principal Acquired | $	[1]	$ 5,785,000
Ocotillo Springs [Member] | Series A [Member] | Brawley, CA [Member]
Schedule Of Available For Sale Securities [Line Items]
Month Acquired	[2]	July
Units | Unit	[2]	75
Maturity Date	[2]	Aug. 01, 2037
Interest Rate	[2],[3]	4.55%
Principal Acquired | $	[2]	$ 2,023,500
Gateway Village [Member] | Durham NC [Member]
Schedule Of Available For Sale Securities [Line Items]
Month Acquired			February
Units | Unit			64
Maturity Date			Apr. 01, 2032
Interest Rate			6.10%
Principal Acquired | $			$ 2,600,000
Lynnhaven Apartments [Member] | Durham NC [Member]
Schedule Of Available For Sale Securities [Line Items]
Month Acquired			February
Units | Unit			75
Maturity Date			Apr. 01, 2032
Interest Rate			6.10%
Principal Acquired | $			$ 3,450,000
Montevista [Member] | Series A [Member] | San Pablo, CA [Member]
Schedule Of Available For Sale Securities [Line Items]
Month Acquired			June
Units | Unit			82
Maturity Date			Jul. 01, 2036
Interest Rate			5.75%
Principal Acquired | $			$ 6,720,000
Montevista [Member] | Series B [Member] | San Pablo, CA [Member]
Schedule Of Available For Sale Securities [Line Items]
Month Acquired			June
Units | Unit			82
Maturity Date			Jul. 01, 2021
Interest Rate			5.75%
Principal Acquired | $			$ 6,480,000

[1] Both MRBs are part of the same series but have different interest rates and maturity dates.

[2] The Partnership has committed to provide total funding of the MRB up to $15.0 million during construction and lease-up of the property on a drawdown basis. Upon stabilization of the property, the MRB will be partially repaid and the maximum balance of the MRB after stabilization is approximately $3.5 million.

[3] The MRB has a variable interest rate equal to 1-month LIBOR plus 3.25%, subject to a floor of 4.55%, during construction of the project until stabilization. Upon stabilization, the MRB will convert to a fixed interest rate of 4.35%.