Debt Financing Footnote XBRL details (Details) (USD $)													3 Months Ended	12 Months Ended										12 Months Ended			6 Months Ended	12 Months Ended		3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended														3 Months Ended									3 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013 Autumn Pines [Member]		Dec. 31, 2012 Autumn Pines [Member]		Dec. 31, 2013 GMF-Warren/Tulane [Member]	Dec. 31, 2013 TEB Facility [Member]	Sep. 30, 2013 TEB Facility [Member] Integer	Dec. 31, 2012 TEB Facility [Member]	Dec. 31, 2011 Class A TEBS Certificates [Member] TEB Facility [Member]	Dec. 31, 2011 Class B TEBS Certificates [Member] TEB Facility [Member]	Mar. 31, 2013 Trust Portfolio--MBS Bonds [Member]	Dec. 31, 2013 Trust Portfolio--MBS Bonds [Member]	Dec. 31, 2012 Trust Portfolio--MBS Bonds [Member]	Jun. 30, 2013 Trust Portfolio--MBS Bonds [Member] Georgia MBS Bonds [Member]	Dec. 31, 2013 Trust Portfolio--MBS Bonds [Member] SPEARS [Member]	Jun. 30, 2013 Trust Portfolio--MBS Bonds [Member] SPEARS [Member] Georgia MBS Bonds [Member]	Dec. 31, 2013 Trust Portfolio--MBS Bonds [Member] LIFERS [Member]	Dec. 31, 2012 Trust Portfolio--MBS Bonds [Member] LIFERS [Member]	Jun. 30, 2013 Trust Portfolio--MBS Bonds [Member] LIFERS [Member] Georgia MBS Bonds [Member]	Dec. 31, 2013 Trading Securities [Member]	Dec. 31, 2012 Trading Securities [Member]	Dec. 31, 2013 Trading Securities [Member] TOB facility-9 [Member]	Dec. 31, 2013 Trading Securities [Member] TOB facility-8 [Member]		Jun. 30, 2013 Trading Securities [Member] TOB facility-7 [Member]	Dec. 31, 2013 Trading Securities [Member] TOB facility-7 [Member]		Mar. 31, 2013 Trading Securities [Member] TOB facility-6 [Member]	Dec. 31, 2013 Trading Securities [Member] TOB facility-6 [Member]	Mar. 31, 2013 Trading Securities [Member] TOB facility-5 [Member]	Dec. 31, 2013 Trading Securities [Member] TOB facility-5 [Member]	Sep. 30, 2013 Trading Securities [Member] TOB facility-5 [Member]	Dec. 31, 2013 Trading Securities [Member] TOB Facility-1 [Member]	Dec. 31, 2012 Trading Securities [Member] TOB Facility-1 [Member]	Dec. 31, 2013 Trading Securities [Member] TOB facility-2 [Member]	Dec. 31, 2012 Trading Securities [Member] TOB facility-2 [Member]	Dec. 31, 2013 Public housing capital fund trusts [Member]	Dec. 31, 2012 Public housing capital fund trusts [Member]	Sep. 30, 2012 Public housing capital fund trusts [Member]	Dec. 31, 2013 Public housing capital fund trusts [Member] SPEARS [Member]	Sep. 30, 2012 Public housing capital fund trusts [Member] SPEARS [Member]	Sep. 30, 2012 Public housing capital fund trusts [Member] LIFERS [Member]	Dec. 31, 2013 TOB Facility [Member]	Dec. 31, 2012 TOB Facility [Member]	Mar. 31, 2013 Five Points Bank [Member]	Mar. 31, 2013 Omaha State Bank [Member]	Dec. 31, 2013 Mortgage Backed Securities Trusts 1 - 5 [Member] Trust Portfolio--MBS Bonds [Member] SPEARS [Member]	Dec. 31, 2012 Mortgage Backed Securities Trusts 1 - 5 [Member] Trust Portfolio--MBS Bonds [Member] SPEARS [Member]	Mar. 31, 2013 Mortgage Backed Security Trust 5 [Member] [Member] Trust Portfolio--MBS Bonds [Member]	Mar. 31, 2013 Mortgage Backed Security Trust 5 [Member] [Member] Trust Portfolio--MBS Bonds [Member] SPEARS [Member]	Mar. 31, 2013 Mortgage Backed Security Trust 5 [Member] [Member] Trust Portfolio--MBS Bonds [Member] LIFERS [Member]	Dec. 31, 2013 Mortgage Backed Security Trust 5 [Member] [Member] Trading Securities [Member] TOB facility-3 [Member]	Dec. 31, 2012 Mortgage Backed Security Trust 5 [Member] [Member] Trading Securities [Member] TOB facility-3 [Member]	Jun. 30, 2013 Mortgage Backed Security Trust 6 [Member] Trading Securities [Member] TOB facility-3 [Member]	Dec. 31, 2013 Mortgage Backed Security Trust 6 [Member] Trading Securities [Member] TOB facility-3 [Member]
Debt financing	$ 257,274,000	$ 177,948,000						$ 92,979,000		$ 94,000,000	$ 95,800,000	$ 20,300,000										$ 164,295,000	$ 83,960,000	$ 25,750,000	$ 13,210,000	[1]		$ 20,000,000	[2]		$ 7,000,000		$ 5,700,000		$ 9,770,000	$ 9,850,000	$ 48,995,000	$ 48,995,000																$ 10,545,000	$ 8,590,000		$ 7,825,000
Available for Sale Securities, not Including Premiums														42,830,000	31,620,000	10,000,000			9,200,000																				65,264,703		65,264,703
TOB Financing																	34,900,000	7,800,000		6,500,000	2,200,000			25,800,000	13,200,000		20,000,000	20,000,000		7,000,000	7,000,000	5,800,000		5,700,000								49,000,000	49,000,000	16,000,000					24,100,000	25,100,000	2,500,000	2,000,000	540,000
Short-term Debt, Percentage Bearing Fixed Interest Rate													0.90%	0.90%										1.60%	1.80%		2.10%	1.80%		2.10%	1.80%	2.10%	1.80%																							0.90%
Cash Collateral for Borrowed Securities														4,100,000																									400,000
Debt Instrument, Basis Spread on Variable Rate													0.30%	0.30%										0.40%	0.40%		0.40%	0.40%		0.50%	0.60%	0.50%	0.60%																							0.10%
Debt Instrument, Total Rate of Borrowing													1.20%	1.20%										1.96%	2.21%	[1]	2.50%	2.21%	[2]	2.60%	2.40%	2.60%	2.40%		1.96%	2.05%	2.32%	2.30%	2.30%	2.30%					2.70%	1.90%								1.27%	1.28%	1.00%	1.02%
Debt Instrument, Interest Rate, Stated Percentage			5.80%	[3]	5.80%	[4]	0.00%	0.10%		0.13%																																						5.00%
Long Term Debt, Maturity date at a point in time																																																Jan. 25, 2014
Debt, Weighted Average Interest Rate								2.00%		2.03%				1.30%	1.30%
Number of Available for Sale Securities, Held in a Trust									13
Line of Credit Facility, Maximum Borrowing Capacity																																															$ 10,000,000	$ 6,000,000
Line of Credit Facility, Interest Rate During Period																																															3.50%

[1] Avistar at Chase Hill, Avistar at the Crest, and Avistar on the Boulevard is the collateral for the approximate $13.2 million TOB Trust.

[2] Avistar at the Oaks Apartments, Avistar on the Hills Apartments, and Avistar in 09 Apartments is the collateral for the $20.0 million TOB Trust.

[3] Bond held by Deutsche Bank in a secured financing transaction, Note 11

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