Fair Value of Financial Instruments - Summary of Activity Related to Level 3 Assets and Liabilities (Details) - Fair Value, Inputs, Level 3 [Member] - USD ($)		3 Months Ended				9 Months Ended
		Sep. 30, 2018		Sep. 30, 2017		Sep. 30, 2018		Sep. 30, 2017		Jan. 01, 2018
Schedule of Available-for-sale Securities [Line Items]
Assets at Fair Value, beginning balance		$ 820,950,642		$ 830,256,024		$ 843,675,611		$ 742,897,488
Assets at Fair Value, Adjusted balance										$ 843,458,663
Total gains (losses) (realized/unrealized) [Abstract]
Total gain (losses) included in earnings (interest income and interest expense)		108,531		(27,929)		1,138,899		(255,825)
Total gain (losses) included in earnings (impairment of securities )		(309,958)				(1,141,020)
Total gain (losses) included in other comprehensive (loss) income		(6,692,749)		2,003,189		(25,528,467)		31,975,966
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases				12,530,217		19,540,000		72,612,017
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		(18,425,540)		(4,018,415)		(41,837,149)		(6,486,560)
Assets at Fair Value, ending balance		795,630,926		840,743,086		795,630,926		840,743,086
Total amount of gains (losses) for the period included in earnings attributable to the change in unrealized gains (losses) relating to assets or liabilities held		(218,279)		(66,917)		(52,960)		(369,686)
Interest rate derivatives [Member]
Schedule of Available-for-sale Securities [Line Items]
Liabilities at Fair value, beginning balance		897,958	[1]	(761,648)	[1]			(955,679)	[2]
Liabilities at Fair value, Adjusted balance	[1]									(229,631)
Total gains (losses) (realized/unrealized) [Abstract]
Total gain (losses) included in earnings (interest income and interest expense)		91,679	[1]	(66,917)	[1]	1,088,060	[1]	(369,686)	[2]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases				59,217	[1]			556,017	[2]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	47,540				178,748
Liabilities at Fair value, ending balance	[1]	1,037,177		(769,348)	[2]	1,037,177		(769,348)	[2]
Total amount of gains (losses) for the period included in earnings attributable to the change in unrealized gains (losses) relating to assets or liabilities held		91,679	[1]	(66,917)	[1]	1,088,060	[1]	(369,686)	[2]
Taxable Mortgage Revenue Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Assets at Fair Value, beginning balance		2,357,952		3,931,471		2,422,459		4,084,599
Assets at Fair Value, Adjusted balance										2,422,459
Total gains (losses) (realized/unrealized) [Abstract]
Total gain (losses) included in other comprehensive (loss) income		(15,192)		2,356		(49,173)		(122,908)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		(2,858)		(4,066)		(33,384)		(31,930)
Assets at Fair Value, ending balance		2,339,902		3,929,761		2,339,902		3,929,761
Bond Purchase Commitment [Member]
Schedule of Available-for-sale Securities [Line Items]
Assets at Fair Value, beginning balance		994,685		3,165,172		3,002,540		2,399,449
Assets at Fair Value, Adjusted balance										3,002,540
Total gains (losses) (realized/unrealized) [Abstract]
Total gain (losses) included in other comprehensive (loss) income		51,760		189,875		(1,956,095)		955,598
Assets at Fair Value, ending balance		1,046,445		3,355,047		1,046,445		3,355,047
Public housing capital fund trusts [Member]
Schedule of Available-for-sale Securities [Line Items]
Assets at Fair Value, beginning balance		49,070,710		55,791,371		49,641,588		57,158,068
Assets at Fair Value, Adjusted balance										49,641,588
Total gains (losses) (realized/unrealized) [Abstract]
Total gain (losses) included in earnings (interest income and interest expense)		(19,274)		(14,129)		(57,822)		(45,846)
Total gain (losses) included in earnings (impairment of securities )		(309,958)				(1,141,020)
Total gain (losses) included in other comprehensive (loss) income				309,808		525,446		(588,172)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements				(1,173,302)		(226,714)		(1,610,302)
Assets at Fair Value, ending balance		48,741,478		54,913,748		48,741,478		54,913,748
Total amount of gains (losses) for the period included in earnings attributable to the change in unrealized gains (losses) relating to assets or liabilities held		(309,958)				(1,141,020)
Mortgage Revenue Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Assets at Fair Value, beginning balance	[3]	767,629,337		768,129,658				680,211,051
Assets at Fair Value, Adjusted balance	[4]									$ 788,621,707
Total gains (losses) (realized/unrealized) [Abstract]
Total gain (losses) included in earnings (interest income and interest expense)		36,126	[3]	53,117	[3]	108,661	[4]	159,707	[3]
Total gain (losses) included in other comprehensive (loss) income		(6,729,317)	[3]	1,501,150	[3]	(24,048,645)	[4]	31,731,448	[3]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases				12,471,000	[3]	19,540,000	[4]	72,056,000	[3]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		(18,470,222)	[3]	(2,841,047)	[3]	(41,755,799)	[4]	(4,844,328)	[3]
Assets at Fair Value, ending balance	[3]	$ 742,465,924	[4]	$ 779,313,878		$ 742,465,924	[4]	$ 779,313,878

[1] Interest rate derivatives include derivative instruments reported in other assets as well as derivative swap liabilities.

[2] Interest rate derivatives include derivative instruments reported in other assets as well as derivative swap liabilities

[3] Mortgage revenue bonds includes both bonds held in trust as well as those held by the Partnership.

[4] Mortgage revenue bonds includes both bonds held in trust as well as those held by the Partnership. The beginning balance also in includes the cumulative effect of accounting change related to the adoption of ASU 2017-08 effective January 1, 2018.