Debt Financing - Additional Information (Details)		1 Months Ended			9 Months Ended		12 Months Ended
		Jul. 31, 2019 USD ($)	Feb. 28, 2019 Agreement	Aug. 31, 2018 USD ($) Security	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2018
Debt Instrument [Line Items]
Amortization of deferred financing costs					$ 1,476,463	$ 1,304,879
Mortgage Revenue Bonds [Member] | Term A/B Trust [Member]
Debt Instrument [Line Items]
Deferred financing costs - net				$ 371,000
Mortgage Revenue Bonds [Member] | Term A/B Trust [Member] | Deutsche Bank [Member]
Debt Instrument [Line Items]
Number of new agreements | Agreement			2
Variable - M24 [Member]
Debt Instrument [Line Items]
Interest rate					3.05%		3.05%
Stated Maturities					2027-05		2027-05
Deferred financing costs - net		$ 307,000
Variable - M24 [Member] | TEBS Financings [Member]
Debt Instrument [Line Items]
Stated Maturities	[1]						2020-09
Variable - M33 [Member]
Debt Instrument [Line Items]
Interest rate					3.24%		3.24%
Stated Maturities					2030-09		2030-09
Deferred financing costs - net		265,000
Amortization of deferred financing costs		496,000
Premium received upon refinancing of debt		$ 435,000
Variable - M33 [Member] | TEBS Financings [Member]
Debt Instrument [Line Items]
Stated Maturities	[2]						2020-07
Fixed - M45 [Member] | TEBS Financings [Member]
Debt Instrument [Line Items]
Stated Maturities	[3]				2034-07		2034-07
Fixed - M45 [Member] | Mortgage Revenue Bonds [Member] | Term A/B Trust [Member]
Debt Instrument [Line Items]
Number of securities collapsed prior to closing of financing | Security				24
Fixed - M45 [Member] | Mortgage Revenue Bonds [Member] | TEBS Financings [Member] | ATAX TEBS IV, LLC [Member]
Debt Instrument [Line Items]
Number of securities provided for long-term debt financing facility | Security				25
Long-term debt financing facility par value				$ 260,600,000

[1] In July 2019, the Partnership refinanced the M24 TEBS Financing with Freddie Mac. After refinancing, the M24 TEBS Financing has a fixed interest rate of 3.05% and a stated maturity of  May 2027.

[2] In July 2019, the Partnership refinanced the M33 TEBS Financing with Freddie Mac. After refinancing, the M33 TEBS Financing has a fixed interest rate of 3.24% and a stated maturity of  September 2030.

[3] The M45 TEBS has an initial interest rate of 3.82% through July 31, 2023. From August 1, 2023 through the stated maturity date, the interest rate is 4.39%. These rates are inclusive of credit enhancement fees payable to Freddie Mac.