Variable Interest Entities Consolidating Balance Sheet (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2011
Assets [Abstract]
Cash and cash equivalents	$ 11,906,607	$ 30,172,773
Restricted cash	7,697,739	5,471,522
Interest receivable	8,012,423	8,473,360
Tax-exempt mortgage revenue bonds held in trust, at fair value	154,914,137	99,534,082
Tax-exempt mortgage revenue bonds, at fair value	48,161,743	45,703,294
Public housing capital fund trusts, at fair value	61,793,516	65,389,298
Available-for-sale Securities, Fair Value Disclosure, Mortgage-backed Securities	38,880,996	32,121,412
Real Estate Assets [Abstract]
Land	12,491,559	11,202,876
Buildings and improvements	115,981,355	93,615,479
Real estate assets before accumulated depreciation	128,472,914	104,818,355
Accumulated depreciation	(23,138,783)	(19,330,063)
Net real estate assets	105,334,131	85,488,292
Other assets	13,353,435	8,216,295
Assets of discontinued operations	0	32,580,427
Assets	450,054,727	413,150,755
Liabilities [Abstract]
Accounts payable, accrued expenses and other liabilities	5,160,479	5,013,947
Distribution payable	5,400,622	5,566,908
Debt financing	226,569,000	177,948,000
Mortgages payable	51,802,031	39,119,507
Liabilities of discontinued operations	0	1,531,462
Bond Purchase Commitment - Fair Market Value Adjustment	4,865,536	0
Liabilities	293,797,668	229,179,824
Partners' Capital
General Partner	84,551	(430,087)
Beneficial Unit Certificate holders	182,079,780	207,383,087
Unallocated deficit of Consolidated VIEs	(25,897,611)	(25,035,808)
Total Partners' Capital	156,266,720	181,917,192
Noncontrolling interest	(9,661)	2,053,739
Total Capital	156,257,059	183,970,931	189,060,549	131,589,045
Total Liabilities and Partners' Capital	450,054,727	413,150,755
Partnership [Member]
Assets [Abstract]
Cash and cash equivalents	11,872,782	30,123,447
Restricted cash	6,444,613	4,538,071
Interest receivable	14,677,455	14,131,063
Tax-exempt mortgage revenue bonds held in trust, at fair value	178,071,670	124,149,600
Tax-exempt mortgage revenue bonds, at fair value	48,161,743	45,703,294
Public housing capital fund trusts, at fair value	61,793,516	65,389,298
Available-for-sale Securities, Fair Value Disclosure, Mortgage-backed Securities	38,880,996	32,121,412
Real Estate Assets [Abstract]
Land	9,241,515	6,798,407
Buildings and improvements	83,656,608	55,776,753
Real estate assets before accumulated depreciation	92,898,123	62,575,160
Accumulated depreciation	(8,382,864)	(5,458,961)
Net real estate assets	84,515,259	57,116,199
Other assets	22,418,827	22,923,356
Assets of discontinued operations		32,580,427
Assets	466,836,861	428,776,167
Liabilities [Abstract]
Accounts payable, accrued expenses and other liabilities	4,413,261	2,330,852
Distribution payable	5,400,622	5,566,908
Debt financing	226,569,000	177,948,000
Mortgages payable	51,802,031	39,119,507
Liabilities of discontinued operations		1,531,462
Bond Purchase Commitment - Fair Market Value Adjustment	4,865,536
Liabilities	293,050,450	226,496,729
Partners' Capital
General Partner	84,551	(430,087)
Beneficial Unit Certificate holders	173,711,521	200,655,786
Unallocated deficit of Consolidated VIEs	0	0
Total Partners' Capital	173,796,072	200,225,699
Noncontrolling interest	(9,661)	2,053,739
Total Capital	173,786,411	202,279,438
Total Liabilities and Partners' Capital	466,836,861	428,776,167
Consolidated VIEs [Member]
Assets [Abstract]
Cash and cash equivalents	33,825	49,326
Restricted cash	1,253,126	933,451
Interest receivable	0	0
Tax-exempt mortgage revenue bonds held in trust, at fair value	0	0
Tax-exempt mortgage revenue bonds, at fair value	0	0
Public housing capital fund trusts, at fair value	0	0
Available-for-sale Securities, Fair Value Disclosure, Mortgage-backed Securities	0	0
Real Estate Assets [Abstract]
Land	3,250,044	4,404,469
Buildings and improvements	32,324,747	37,838,726
Real estate assets before accumulated depreciation	35,574,791	42,243,195
Accumulated depreciation	(14,755,919)	(13,871,102)
Net real estate assets	20,818,872	28,372,093
Other assets	597,081	852,321
Assets of discontinued operations		0
Assets	22,702,904	30,207,191
Liabilities [Abstract]
Accounts payable, accrued expenses and other liabilities	28,761,746	28,529,405
Distribution payable	0	0
Debt financing	0	0
Mortgages payable	23,960,000	24,158,000
Liabilities of discontinued operations		0
Bond Purchase Commitment - Fair Market Value Adjustment	0
Liabilities	52,721,746	52,687,405
Partners' Capital
General Partner	0	0
Beneficial Unit Certificate holders	0	0
Unallocated deficit of Consolidated VIEs	(30,018,842)	(22,480,214)
Total Partners' Capital	(30,018,842)	(22,480,214)
Noncontrolling interest	0	0
Total Capital	(30,018,842)	(22,480,214)
Total Liabilities and Partners' Capital	22,702,904	30,207,191
Consolidations, Eliminations for VIEs [Member]
Assets [Abstract]
Cash and cash equivalents	0	0
Restricted cash	0	0
Interest receivable	(6,665,032)	(5,657,703)
Tax-exempt mortgage revenue bonds held in trust, at fair value	(23,157,533)	(24,615,518)
Tax-exempt mortgage revenue bonds, at fair value	0	0
Public housing capital fund trusts, at fair value	0	0
Available-for-sale Securities, Fair Value Disclosure, Mortgage-backed Securities	0	0
Real Estate Assets [Abstract]
Land	0	0
Buildings and improvements	0	0
Real estate assets before accumulated depreciation	0	0
Accumulated depreciation	0	0
Net real estate assets	0	0
Other assets	(9,662,473)	(15,559,382)
Assets of discontinued operations		0
Assets	(39,485,038)	(45,832,603)
Liabilities [Abstract]
Accounts payable, accrued expenses and other liabilities	(28,014,528)	(25,846,310)
Distribution payable	0	0
Debt financing	0	0
Mortgages payable	(23,960,000)	(24,158,000)
Liabilities of discontinued operations		0
Bond Purchase Commitment - Fair Market Value Adjustment	0
Liabilities	(51,974,528)	(50,004,310)
Partners' Capital
General Partner	0	0
Beneficial Unit Certificate holders	8,368,259	6,727,301
Unallocated deficit of Consolidated VIEs	4,121,231	(2,555,594)
Total Partners' Capital	12,489,490	4,171,707
Noncontrolling interest	0	0
Total Capital	12,489,490	4,171,707
Total Liabilities and Partners' Capital	$ (39,485,038)	$ (45,832,603)