Investments in Tax-Exempt Bonds (Details) (USD $)	Dec. 31, 2012		Sep. 30, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Cost adjusted for pay-downs, held in trust	$ 88,257,386			$ 104,231,732
Cost adjusted for pay-downs			48,827,485	31,382,000
Unrealized Gain, held in trust	11,277,142			6,707,781
Unrealized Gain			1,165,695	160,658
Unrealized Loss, held in trust	(446)			(1,786,726)
Unrealized Loss			(4,289,886)	(5,000,093)
Estimated Fair Value, held in trust	99,534,082			109,152,787
Estimated Fair Value	45,703,294		45,703,294	26,542,565
Ashley Square [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost adjusted for pay-downs, held in trust	5,260,000	[1]		5,308,000	[1]
Unrealized Gain, held in trust	246,981	[1]		0	[1]
Unrealized Loss, held in trust	0	[1]		0	[1]
Estimated Fair Value, held in trust	5,506,981	[1]		5,308,000	[1]
Autumn Pines [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost adjusted for pay-downs, held in trust	12,217,004	[2]		12,280,776	[2]
Unrealized Gain, held in trust	953,024	[2]		0	[2]
Unrealized Loss, held in trust	0	[2]		(152,094)	[2]
Estimated Fair Value, held in trust	13,170,028	[2]		12,128,682	[2]
Bella Vista [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost adjusted for pay-downs, held in trust	6,600,000	[1]		6,650,000	[1]
Unrealized Gain, held in trust	93,324	[1]		0	[1]
Unrealized Loss, held in trust	0	[1]		(405,184)	[1]
Estimated Fair Value, held in trust	6,693,324	[1]		6,244,816	[1]
Bridle Ridge [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost adjusted for pay-downs, held in trust	7,765,000	[1]		7,815,000	[1]
Unrealized Gain, held in trust	108,632	[1]		0	[1]
Unrealized Loss, held in trust	0	[1]		(469,056)	[1]
Estimated Fair Value, held in trust	7,873,632	[1]		7,345,944	[1]
Brookstone [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost adjusted for pay-downs, held in trust	7,453,246	[1]		7,437,947	[1]
Unrealized Gain, held in trust	1,459,408	[1]		1,116,538	[1]
Unrealized Loss, held in trust	0	[1]		0	[1]
Estimated Fair Value, held in trust	8,912,654	[1]		8,554,485	[1]
Cross Creek [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost adjusted for pay-downs, held in trust	6,004,424	[1]		5,961,478	[1]
Unrealized Gain, held in trust	1,994,911	[1]		1,824,167	[1]
Unrealized Loss, held in trust	0	[1]		0	[1]
Estimated Fair Value, held in trust	7,999,335	[1]		7,785,645	[1]
GMF-Madison Tower [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost adjusted for pay-downs, held in trust				3,810,000
Unrealized Gain, held in trust				51,130
Unrealized Loss, held in trust				0
Estimated Fair Value, held in trust				3,861,130
GMF-Warren/Tulane [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost adjusted for pay-downs, held in trust				11,815,000
Unrealized Gain, held in trust				321,722
Unrealized Loss, held in trust				0
Estimated Fair Value, held in trust				12,136,722
Lost Creek [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost adjusted for pay-downs, held in trust	15,987,744	[1]		16,051,048	[1]
Unrealized Gain, held in trust	3,467,182	[1]		1,962,587	[1]
Unrealized Loss, held in trust	0	[1]		0	[1]
Estimated Fair Value, held in trust	19,454,926	[1]		18,013,635	[1]
Runnymede [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost adjusted for pay-downs, held in trust	10,605,000	[1]		10,685,000	[1]
Unrealized Gain, held in trust	491,330	[1]		0	[1]
Unrealized Loss, held in trust	0	[1]		(434,452)	[1]
Estimated Fair Value, held in trust	11,096,330	[1]		10,250,548	[1]
Southpark [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost adjusted for pay-downs, held in trust	11,904,968	[1]		11,925,483	[1]
Unrealized Gain, held in trust	2,462,350	[1]		1,431,637	[1]
Unrealized Loss, held in trust	0	[1]		0	[1]
Estimated Fair Value, held in trust	14,367,318	[1]		13,357,120	[1]
Woodlynn Village [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost adjusted for pay-downs, held in trust	4,460,000	[1]		4,492,000	[1]
Unrealized Gain, held in trust	0	[1]		0	[1]
Unrealized Loss, held in trust	(446)	[1]		(325,940)	[1]
Estimated Fair Value, held in trust	4,459,554	[1]		4,166,060	[1]
Arbors at Hickory Ridge [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost adjusted for pay-downs	11,581,485
Unrealized Gain	610,785
Unrealized Loss	0
Estimated Fair Value	12,192,270
Iona Lakes [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost adjusted for pay-downs	15,535,000			15,720,000
Unrealized Gain	554,910			160,658
Unrealized Loss	0			0
Estimated Fair Value	16,089,910			15,880,658
Vantage at Judson [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost adjusted for pay-downs	6,049,000
Unrealized Gain	0
Unrealized Loss	(847)
Estimated Fair Value	6,048,153
Woodland Park [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost adjusted for pay-downs	15,662,000			15,662,000
Unrealized Gain	0			0
Unrealized Loss	(4,289,039)			(5,000,093)
Estimated Fair Value	$ 11,372,961			$ 10,661,907

[1] Bonds owned by ATAX TEBS I, LLC, Note 11

[2] Bond held by Duetsche Bank in a secured financing transaction, Note 11