Mortgage Revenue Bonds - Schedule of MRB Redeemed (Details)		3 Months Ended
		Mar. 31, 2021 USD ($) Unit	Mar. 31, 2020 USD ($) Unit
Schedule Of Available For Sale Securities [Line Items]
Units | Unit		3,468
Mortgage Revenue Bonds [Member]
Schedule Of Available For Sale Securities [Line Items]
Principal Outstanding at Date of Redemption | $		$ 7,385,000
Mortgage Revenue Bonds [Member] | Arby Road Apartments [Member] | Series A [Member] | Las Vegas, NV [Member]
Schedule Of Available For Sale Securities [Line Items]
Month Redeemed	[1]	March
Units | Unit	[1]	180
Original Maturity Date	[1]	Oct. 01, 2027
Interest Rate	[1]	5.35%
Principal Outstanding at Date of Redemption | $	[1]	$ 1,600,000
Mortgage Revenue Bonds [Member] | Arby Road Apartments [Member] | Series A [Member] | Las Vegas, NV [Member]
Schedule Of Available For Sale Securities [Line Items]
Month Redeemed	[1]	March
Units | Unit	[1]	180
Original Maturity Date	[1]	Apr. 01, 2041
Interest Rate	[1]	5.50%
Principal Outstanding at Date of Redemption | $	[1]	$ 5,785,000
Mortgage Revenue Bonds [Member] | Solano Vista [Member] | Series B [Member] | Vallejo, CA [Member]
Schedule Of Available For Sale Securities [Line Items]
Month Redeemed			January
Units | Unit			96
Original Maturity Date			Jan. 01, 2021
Interest Rate			5.85%
Principal Outstanding at Date of Redemption | $			$ 3,103,000

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