Summary of Activity Related to Level 3 Assets and Liabilities (Details) - Fair Value, Inputs, Level 3 [Member] - USD ($)		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Assets at Fair Value, beginning balance		$ 742,897,488	$ 653,875,949
Total gains (losses) (realized/unrealized) [Abstract]
Total gain (losses) included in earnings (interest income and interest expense)		(85,582)	(1,110,407)
Total gain (losses) included in other comprehensive (loss) income		19,201,310	13,925,240
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		59,585,000	11,500,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sale of securities			(9,747,524)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		(1,117,951)	(1,484,976)
Assets at Fair Value, ending balance		820,480,265	666,958,282
Total amount of losses for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held		(121,349)	(1,110,407)
Interest rate derivatives [Member]
Schedule of Available-for-sale Securities [Line Items]
Liabilities at Fair value, beginning balance	[1]	(955,679)	(972,898)
Total gains (losses) (realized/unrealized) [Abstract]
Total gain (losses) included in earnings (interest income and interest expense)	[1]	(121,349)	(1,110,407)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sale of securities	[1]		(399)
Liabilities at Fair value, ending balance	[1]	(1,077,028)	(2,083,704)
Total amount of losses for the period included in earnings attributable to the change in unrealized gains or losses relating to assets or liabilities still held	[1]	(121,349)	(1,110,407)
Bond Purchase Commitment [Member]
Schedule of Available-for-sale Securities [Line Items]
Assets at Fair Value, beginning balance		2,399,449	5,634,360
Total gains (losses) (realized/unrealized) [Abstract]
Total gain (losses) included in other comprehensive (loss) income		220,944	1,587,813
Assets at Fair Value, ending balance		2,620,393	7,222,173
PHC Certificates [Member]
Schedule of Available-for-sale Securities [Line Items]
Assets at Fair Value, beginning balance		57,158,068	60,707,290
Total gains (losses) (realized/unrealized) [Abstract]
Total gain (losses) included in earnings (interest income and interest expense)		(17,588)
Total gain (losses) included in other comprehensive (loss) income		(1,288,681)	869,344
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements			(1,071,294)
Assets at Fair Value, ending balance		55,851,799	60,505,340
Taxable Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Assets at Fair Value, beginning balance		4,084,599	4,824,060
Total gains (losses) (realized/unrealized) [Abstract]
Total gain (losses) included in other comprehensive (loss) income		98,494	116,456
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		(3,888)	(2,412)
Assets at Fair Value, ending balance		4,179,205	4,938,104
Mortgage Revenue Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Assets at Fair Value, beginning balance	[2]	680,211,051	583,683,137
Total gains (losses) (realized/unrealized) [Abstract]
Total gain (losses) included in earnings (interest income and interest expense)	[2]	53,355
Total gain (losses) included in other comprehensive (loss) income	[2]	20,170,553	11,351,627
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[2]	59,585,000	11,500,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sale of securities	[2]		(9,747,125)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[2]	(1,114,063)	(411,270)
Assets at Fair Value, ending balance	[2]	$ 758,905,896	$ 596,376,369

[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.