Fair Value Measurements Available for sale securities (Details) (USD $)	9 Months Ended													3 Months Ended		9 Months Ended				3 Months Ended		9 Months Ended				3 Months Ended		9 Months Ended						3 Months Ended		9 Months Ended				3 Months Ended		9 Months Ended																																															9 Months Ended	12 Months Ended	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Sep. 30, 2013 Tax-exempt mortgage revenue bonds [Member]	Dec. 31, 2012 Tax-exempt mortgage revenue bonds [Member]	Sep. 30, 2013 Public housing capital fund trusts [Member]	Dec. 31, 2012 Public housing capital fund trusts [Member]	Sep. 30, 2013 Trust Portfolio--MBS Bonds [Member]	Dec. 31, 2012 Trust Portfolio--MBS Bonds [Member]	Sep. 30, 2013 Taxable Bonds [Member]	Dec. 31, 2012 Taxable Bonds [Member]	Sep. 30, 2013 Interest rate derivatives [Member]	Dec. 31, 2012 Interest rate derivatives [Member]	Sep. 30, 2013 Fair Value, Inputs, Level 3 [Member]	Sep. 30, 2012 Fair Value, Inputs, Level 3 [Member]	Sep. 30, 2013 Fair Value, Inputs, Level 3 [Member]	Sep. 30, 2012 Fair Value, Inputs, Level 3 [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member]	Sep. 30, 2013 Fair Value, Inputs, Level 3 [Member] Tax-exempt mortgage revenue bonds [Member]	Sep. 30, 2012 Fair Value, Inputs, Level 3 [Member] Tax-exempt mortgage revenue bonds [Member]	Sep. 30, 2013 Fair Value, Inputs, Level 3 [Member] Tax-exempt mortgage revenue bonds [Member]	Sep. 30, 2012 Fair Value, Inputs, Level 3 [Member] Tax-exempt mortgage revenue bonds [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member] Tax-exempt mortgage revenue bonds [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Tax-exempt mortgage revenue bonds [Member]	Sep. 30, 2013 Fair Value, Inputs, Level 3 [Member] Public housing capital fund trusts [Member]	Sep. 30, 2012 Fair Value, Inputs, Level 3 [Member] Public housing capital fund trusts [Member]	Sep. 30, 2013 Fair Value, Inputs, Level 3 [Member] Public housing capital fund trusts [Member]	Sep. 30, 2012 Fair Value, Inputs, Level 3 [Member] Public housing capital fund trusts [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member] Public housing capital fund trusts [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Public housing capital fund trusts [Member]	Sep. 30, 2013 Fair Value, Inputs, Level 3 [Member] Trust Portfolio--MBS Bonds [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Trust Portfolio--MBS Bonds [Member]	Sep. 30, 2013 Fair Value, Inputs, Level 3 [Member] Taxable Bonds [Member]	Sep. 30, 2012 Fair Value, Inputs, Level 3 [Member] Taxable Bonds [Member]	Sep. 30, 2013 Fair Value, Inputs, Level 3 [Member] Taxable Bonds [Member]	Sep. 30, 2012 Fair Value, Inputs, Level 3 [Member] Taxable Bonds [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member] Taxable Bonds [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Taxable Bonds [Member]	Sep. 30, 2013 Fair Value, Inputs, Level 3 [Member] Interest rate derivatives [Member]	Sep. 30, 2012 Fair Value, Inputs, Level 3 [Member] Interest rate derivatives [Member]	Sep. 30, 2013 Fair Value, Inputs, Level 3 [Member] Interest rate derivatives [Member]	Sep. 30, 2012 Fair Value, Inputs, Level 3 [Member] Interest rate derivatives [Member]	Mar. 31, 2013 Fair Value, Inputs, Level 3 [Member] Interest rate derivatives [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Interest rate derivatives [Member]	Sep. 30, 2013 Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 1 [Member]	Sep. 30, 2013 Fair Value, Inputs, Level 1 [Member] Tax-exempt mortgage revenue bonds [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 1 [Member] Tax-exempt mortgage revenue bonds [Member]	Sep. 30, 2013 Fair Value, Inputs, Level 1 [Member] Public housing capital fund trusts [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 1 [Member] Public housing capital fund trusts [Member]	Sep. 30, 2013 Fair Value, Inputs, Level 1 [Member] Trust Portfolio--MBS Bonds [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 1 [Member] Trust Portfolio--MBS Bonds [Member]	Sep. 30, 2013 Fair Value, Inputs, Level 1 [Member] Taxable Bonds [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 1 [Member] Taxable Bonds [Member]	Sep. 30, 2013 Fair Value, Inputs, Level 1 [Member] Interest rate derivatives [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 1 [Member] Interest rate derivatives [Member]	Sep. 30, 2013 Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 2 [Member]	Sep. 30, 2013 Fair Value, Inputs, Level 2 [Member] Tax-exempt mortgage revenue bonds [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 2 [Member] Tax-exempt mortgage revenue bonds [Member]	Sep. 30, 2013 Fair Value, Inputs, Level 2 [Member] Public housing capital fund trusts [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 2 [Member] Public housing capital fund trusts [Member]	Sep. 30, 2013 Fair Value, Inputs, Level 2 [Member] Trust Portfolio--MBS Bonds [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 2 [Member] Trust Portfolio--MBS Bonds [Member]	Sep. 30, 2013 Fair Value, Inputs, Level 2 [Member] Taxable Bonds [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 2 [Member] Taxable Bonds [Member]	Sep. 30, 2013 Fair Value, Inputs, Level 2 [Member] Interest rate derivatives [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 2 [Member] Interest rate derivatives [Member]	Mar. 31, 2013 Ohio Properties [Member]	Sep. 30, 2013 Ohio Properties [Member] Fair Value, Inputs, Level 3 [Member]	Sep. 30, 2013 Ohio Properties [Member] Fair Value, Inputs, Level 3 [Member] Tax-exempt mortgage revenue bonds [Member]	Sep. 30, 2013 Ohio Properties [Member] Fair Value, Inputs, Level 3 [Member] Public housing capital fund trusts [Member]	Sep. 30, 2013 Ohio Properties [Member] Fair Value, Inputs, Level 3 [Member] Taxable Bonds [Member]	Sep. 30, 2013 Ohio Properties [Member] Fair Value, Inputs, Level 3 [Member] Interest rate derivatives [Member]	Sep. 30, 2013 Greens of Pine Glen [Member]		Sep. 30, 2013 Greens of Pine Glen [Member] Fair Value, Inputs, Level 3 [Member]	Sep. 30, 2013 Greens of Pine Glen [Member] Fair Value, Inputs, Level 3 [Member] Tax-exempt mortgage revenue bonds [Member]	Sep. 30, 2013 Greens of Pine Glen [Member] Fair Value, Inputs, Level 3 [Member] Public housing capital fund trusts [Member]	Sep. 30, 2013 Greens of Pine Glen [Member] Fair Value, Inputs, Level 3 [Member] Taxable Bonds [Member]	Sep. 30, 2013 Greens of Pine Glen [Member] Fair Value, Inputs, Level 3 [Member] Interest rate derivatives [Member]	Dec. 31, 2012 Iona Lakes [Member]	Sep. 30, 2013 Iona Lakes [Member] Fair Value, Inputs, Level 3 [Member]	Sep. 30, 2013 Iona Lakes [Member] Fair Value, Inputs, Level 3 [Member] Tax-exempt mortgage revenue bonds [Member]	Sep. 30, 2013 Iona Lakes [Member] Fair Value, Inputs, Level 3 [Member] Public housing capital fund trusts [Member]	Sep. 30, 2013 Iona Lakes [Member] Fair Value, Inputs, Level 3 [Member] Taxable Bonds [Member]	Sep. 30, 2013 Iona Lakes [Member] Fair Value, Inputs, Level 3 [Member] Interest rate derivatives [Member]	Sep. 30, 2013 Woodland Park [Member]	Dec. 31, 2012 Woodland Park [Member]	Sep. 30, 2013 Woodland Park [Member] Fair Value, Inputs, Level 3 [Member]	Sep. 30, 2013 Woodland Park [Member] Fair Value, Inputs, Level 3 [Member] Tax-exempt mortgage revenue bonds [Member]	Sep. 30, 2013 Woodland Park [Member] Fair Value, Inputs, Level 3 [Member] Public housing capital fund trusts [Member]	Sep. 30, 2013 Woodland Park [Member] Fair Value, Inputs, Level 3 [Member] Taxable Bonds [Member]	Sep. 30, 2013 Woodland Park [Member] Fair Value, Inputs, Level 3 [Member] Interest rate derivatives [Member]
Schedule of Available-for-sale Securities [Line Items]
Equity Method Investment, Quoted Market Value																																														$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0
Fair Value, Assets and Liabilities Measured on Recurring/Nonrecurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Fair Value Disclosure	243,850,960			203,075,880	145,237,376	61,793,516	65,389,298	38,880,996	32,121,412	4,139,878	724,145	867,643	378,729		138,101,148	212,530,276	137,793,568	265,473,415			136,846,619	145,237,376	135,695,352	199,115,593			0	65,389,298	0	62,759,268					711,756	1,524,873	774,946	3,083,579			542,773	378,729	1,323,270	514,975
Total gains (lossses) (realized/unrealized) [Abstract]
Gain (Loss) on Investments														(440,331)	(274,814)	(304,085)	(1,055,311)			0	0	0	0			0	0	0	0					0	0	0	0			(440,331)	(274,814)	(304,085)	(1,055,311)
Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Income (Loss), before Tax, Including Portion Attributable to Noncontrolling Interest, Available-for-sale Securities														(17,174,260)	2,121,836	(19,637,948)	9,043,888			(15,995,937)	1,917,241	(15,851,561)	8,806,812			(951,622)	192,206	(3,553,392)	192,206					(226,701)	12,389	(232,995)	44,870			0	0	0	0
Tax-exempt mortgage revenue bonds held in trust, at fair value	154,914,137		99,534,082											9,465,000		9,465,000				9,465,000		9,465,000				0		0						0		0				0		0																													19,581,166	19,581,166	0	0	0	9,098,751	[1]	9,465,000	9,465,000	0	0	0
Deriviative at purchase price	800,000													792,999		792,999				0		0				0		0						0		0				792,999		792,999
Foreclosure of Available-for-Sale Securities	4,080,734																																																																																								1,278,124	0	(11,581,266)	(11,581,266)	0	0	0
Tax-exempt mortgage revenue bonds, at fair value	48,161,743		45,703,294																							0		0						0		0				792,999		792,999																												19,800,000													16,089,910	(16,052,849)	(16,052,849)	0	0	0		11,372,961
Assets, Fair Value Disclosure	308,757,913			203,075,880	145,237,376	61,793,516	65,389,298	38,880,996	32,121,412	4,139,878	724,145	867,643	378,729	269,876,917	205,958,137	269,876,917	205,958,137	265,473,415		203,075,880	138,802,064	203,075,880	138,802,064	199,115,593		61,793,516	66,163,969	61,793,516	66,163,969	62,759,268				4,139,878	724,145	4,139,878	724,145	3,083,579		867,643	267,959	867,643	267,959	514,975
Fair Value Observable inputs (level 2)																																																										38,880,996	32,121,412	0	0	0	0	38,880,996	32,121,412	0	0	0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value														11,825,000	65,986,385	75,670,000	76,151,200			10,542,000	472	72,752,000	10,165,287			0	65,985,913	0	65,985,913					1,283,000	0	2,918,000	0			0	0	0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements														(64,906)	23,582	(586,376)	(350,208)			(50,776)	37,732	(473,986)	(240,387)			(14,130)	(14,150)	(42,390)	(14,150)					0	0	(70,000)	(95,671)			0	0	0	0
Proceeds from Maturities, Prepayments and Calls of Available-for-sale Securities	1,776,418	666,458															(15,625,000)						(15,625,000)						0								0						0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value														$ 269,876,917		$ 269,876,917			$ 211,729,548	$ 203,075,880		$ 203,075,880			$ 145,237,376	$ 61,793,516		$ 61,793,516			$ 65,389,298	$ 0	$ 0	$ 4,139,878		$ 4,139,878			$ 724,145	$ 867,643		$ 867,643			$ 378,729

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