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
		Mar. 31, 2018		Mar. 31, 2017		Jan. 01, 2018
Schedule of Available-for-sale Securities [Line Items]
Assets at Fair Value, beginning balance		$ 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)		1,007,035		(85,582)
Total gain (losses) included in other comprehensive (loss) income		(22,849,943)		19,201,310
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases				59,585,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		(11,439,047)		(1,117,951)
Assets at Fair Value, ending balance		810,176,708		820,480,265
Total amount of losses for the period included in earnings attributable to the change in unrealized gains (losses) relating to assets or liabilities held		989,995		(121,349)
Interest rate derivatives [Member]
Schedule of Available-for-sale Securities [Line Items]
Liabilities at Fair value, beginning balance	[1]			(955,679)
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)	[1]	989,995		(121,349)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	92,338
Liabilities at Fair value, ending balance	[1]	852,702		(1,077,028)
Total amount of losses for the period included in earnings attributable to the change in unrealized gains (losses) relating to assets or liabilities held	[1]	989,995		(121,349)
Bond Purchase Commitment [Member]
Schedule of Available-for-sale Securities [Line Items]
Assets at Fair Value, beginning balance		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		(975,067)		220,944
Assets at Fair Value, ending balance		2,027,473		2,620,393
Public housing capital fund trusts [Member]
Schedule of Available-for-sale Securities [Line Items]
Assets at Fair Value, beginning balance		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)		(17,588)
Total gain (losses) included in other comprehensive (loss) income		(456,346)		(1,288,681)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		(226,714)
Assets at Fair Value, ending balance		48,939,254		55,851,799
Taxable Mortgage Revenue Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Assets at Fair Value, beginning balance		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		(21,902)		98,494
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		(2,732)		(3,888)
Assets at Fair Value, ending balance		2,397,825		4,179,205
Mortgage Revenue Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Assets at Fair Value, beginning balance	[2]			680,211,051
Assets at Fair Value, Adjusted balance	[3]					$ 788,621,707
Total gains (losses) (realized/unrealized) [Abstract]
Total gain (losses) included in earnings (interest income and interest expense)		36,314	[3]	53,355	[2]
Total gain (losses) included in other comprehensive (loss) income		(21,396,628)	[3]	20,170,553	[2]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[2]			59,585,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		(11,301,939)	[3]	(1,114,063)	[2]
Assets at Fair Value, ending balance		$ 755,959,454	[3]	$ 758,905,896	[2]

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

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

[3] 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.