Debt Financing Footnote XBRL details (Details) (USD $)	Feb. 28, 2013	Dec. 31, 2012 credit	Dec. 31, 2011	Dec. 31, 2012 Autumn Pines [Member]		Sep. 30, 2012 Autumn Pines [Member]	Dec. 31, 2011 Autumn Pines [Member]		Jul. 31, 2011 Autumn Pines [Member]	Dec. 31, 2012 GMF-Warren/Tulane [Member]	Dec. 31, 2011 GMF-Warren/Tulane [Member]		Jul. 31, 2011 GMF-Warren/Tulane [Member]	Dec. 31, 2012 TOB facility-3 [Member] Integer	Dec. 31, 2012 TEB Facility [Member]	Jun. 30, 2012 TEB Facility [Member]	Dec. 31, 2011 TEB Facility [Member]	Sep. 30, 2010 TEB Facility [Member] Integer	Dec. 31, 2010 Class A TEBS Certificates [Member] TEB Facility [Member]	Dec. 31, 2010 Class B TEBS Certificates [Member] TEB Facility [Member]	Dec. 31, 2012 Trust Portfolio--MBS Bonds [Member]	Dec. 31, 2012 Trust Portfolio--MBS Bonds [Member] SPEARS [Member]	Dec. 31, 2012 Trust Portfolio--MBS Bonds [Member] LIFERS [Member]	Sep. 30, 2012 Public housing capital fund trusts [Member]	Jun. 30, 2012 Public housing capital fund trusts [Member]	Sep. 30, 2012 Public housing capital fund trusts [Member] SPEARS [Member]	Jun. 30, 2012 Public housing capital fund trusts [Member] SPEARS [Member]	Sep. 30, 2012 Public housing capital fund trusts [Member] LIFERS [Member]	Jun. 30, 2012 Public housing capital fund trusts [Member] LIFERS [Member]
Derivative, Average Variable Interest Rate		2.07%	2.60%
Debt financing		$ 177,948,000	$ 112,673,000												$ 93,988,000		$ 94,933,000		$ 95,800,000	$ 20,300,000
Number of Credit Facilities		3
Available for Sale Securities, not Including Premiums																					31,620,000			65,264,703	65,300,000
TOB Financing			17,700,000			9,800,000			10,000,000				7,800,000									25,100,000	6,500,000			49,000,000	49,000,000	16,000,000	16,000,000
Available for Sale Securities at Par Value		123,630,203	124,648,502						13,400,000				15,600,000
Debt Instrument, Interest Rate, Stated Percentage	9.00%			5.80%	[1]		5.80%	[1]		0.00%	6.75%	[1]			0.13%		0.15%
Debt, Weighted Average Interest Rate																2.03%	2.05%
Number of Available for Sale Securities, Held in a Trust														5				13
Long-term Debt, Current Maturities		$ 13,339,707

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