Variable Interest Entities Consolidating Balance Sheet (Details) (USD $)	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011	Dec. 31, 2010
Cash and cash equivalents	$ 81,790,870	$ 20,201,573
Restricted cash	6,419,577	13,852,753
Interest receivable	7,083,519	6,984,978
Tax-exempt mortgage revenue bonds held in trust, at fair value	98,707,622	109,152,787
Tax-exempt mortgage revenue bonds, at fair value	38,138,997	26,542,565
Land	13,802,148	12,430,434
Buildings and improvements	114,355,138	111,653,203
Real estate assets before accumulated depreciation	128,157,286	124,083,637
Accumulated depreciation	(22,402,643)	(19,817,998)
Net real estate assets	105,754,643	104,265,639
Other assets	8,552,585	10,211,388
Assets of discontinued operations	6,698,871	6,764,862
Assets	353,146,684	297,976,545
Accounts payable, accrued expenses and other liabilities	3,596,921	3,491,642
Distribution payable	5,562,518	3,911,340
Debt financing	104,328,000	112,673,000
Mortgages payable	43,231,990	40,092,455
Liabilities of discontinued operations	6,131,925	6,219,063
Liabilities	162,851,354	166,387,500
General Partner	(364,091)	(354,006)
Beneficial Unit Certificate holders	213,861,059	154,911,228
Unallocated deficit of Consolidated VIEs	(24,011,830)	(23,512,962)
Partners' Capital	189,485,138	131,044,260
Noncontrolling interest	810,192	544,785
Total Partners Capital	190,295,330	131,589,045	138,995,275	128,021,565
Liabilities and Equity	353,146,684	297,976,545
Partnership [Member]
Cash and cash equivalents	81,738,675	20,188,855
Restricted cash	5,426,851	12,915,700
Interest receivable	12,104,935	11,395,266
Tax-exempt mortgage revenue bonds held in trust, at fair value	123,353,050	132,920,723
Tax-exempt mortgage revenue bonds, at fair value	38,138,997	26,542,565
Land	10,552,104	9,180,390
Buildings and improvements	82,601,481	80,045,210
Real estate assets before accumulated depreciation	93,153,585	89,225,600
Accumulated depreciation	(9,373,669)	(7,485,664)
Net real estate assets	83,779,916	81,739,936
Other assets	18,121,728	20,222,928
Assets of discontinued operations	6,698,871	6,764,862
Assets	369,363,023	312,690,835
Accounts payable, accrued expenses and other liabilities	2,624,822	2,516,851
Distribution payable	5,562,518	3,911,340
Debt financing	104,328,000	112,673,000
Mortgages payable	43,231,990	40,092,455
Liabilities of discontinued operations	6,131,925	6,219,063
Liabilities	161,879,255	165,412,709
General Partner	(364,091)	(354,006)
Beneficial Unit Certificate holders	207,037,667	147,087,347
Unallocated deficit of Consolidated VIEs	0	0
Partners' Capital	206,673,576	146,733,341
Noncontrolling interest	810,192	544,785
Total Partners Capital	207,483,768	147,278,126
Liabilities and Equity	369,363,023	312,690,835
Consolidated VIEs [Member]
Cash and cash equivalents	52,195	12,718
Restricted cash	992,726	937,053
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
Land	3,250,044	3,250,044
Buildings and improvements	31,753,657	31,607,993
Real estate assets before accumulated depreciation	35,003,701	34,858,037
Accumulated depreciation	(13,028,974)	(12,332,334)
Net real estate assets	21,974,727	22,525,703
Other assets	794,620	839,879
Assets of discontinued operations	0	0
Assets	23,814,268	24,315,353
Accounts payable, accrued expenses and other liabilities	25,763,858	24,780,781
Distribution payable	0	0
Debt financing	0	0
Mortgages payable	24,284,000	24,407,000
Liabilities of discontinued operations	0	0
Liabilities	50,047,858	49,187,781
General Partner	0	0
Beneficial Unit Certificate holders	0	0
Unallocated deficit of Consolidated VIEs	(26,233,590)	(24,872,428)
Partners' Capital	(26,233,590)	(24,872,428)
Noncontrolling interest	0	0
Total Partners Capital	(26,233,590)	(24,872,428)
Liabilities and Equity	23,814,268	24,315,353
Consolidations, Eliminations for VIEs [Member]
Cash and cash equivalents	0	0
Restricted cash	0	0
Interest receivable	(5,021,416)	(4,410,288)
Tax-exempt mortgage revenue bonds held in trust, at fair value	(24,645,428)	(23,767,936)
Tax-exempt mortgage revenue bonds, at fair value	0	0
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	(10,363,763)	(10,851,419)
Assets of discontinued operations	0	0
Assets	(40,030,607)	(39,029,643)
Accounts payable, accrued expenses and other liabilities	(24,791,759)	(23,805,990)
Distribution payable	0	0
Debt financing	0	0
Mortgages payable	(24,284,000)	(24,407,000)
Liabilities of discontinued operations	0	0
Liabilities	(49,075,759)	(48,212,990)
General Partner	0	0
Beneficial Unit Certificate holders	6,823,392	7,823,881
Unallocated deficit of Consolidated VIEs	2,221,760	1,359,466
Partners' Capital	9,045,152	9,183,347
Noncontrolling interest	0	0
Total Partners Capital	9,045,152	9,183,347
Liabilities and Equity	$ (40,030,607)	$ (39,029,643)