Variable Interest Entities Property Asset Carrying Value and Maximum Exposure (Details) (USD $)	Dec. 31, 2012	Dec. 31, 2011
Ashley Square [Member]
Maximum Exposure to Loss	$ 11,835,664	$ 11,425,528
Carrying Value	6,804,981	6,498,000
Ashley Square [Member] | Tax-exempt mortgage revenue bonds [Member]
Maximum Exposure to Loss	5,260,000	5,308,000
Carrying Value	5,506,981	5,308,000
Ashley Square [Member] | Property Loan [Member]
Maximum Exposure to Loss	6,575,664	6,117,528
Carrying Value	1,298,000	1,190,000
Cross Creek [Member]
Maximum Exposure to Loss	9,388,039	9,526,233
Carrying Value	11,382,950	11,350,400
Cross Creek [Member] | Tax-exempt mortgage revenue bonds [Member]
Maximum Exposure to Loss	6,004,424	5,961,478
Carrying Value	7,999,335	7,785,645
Cross Creek [Member] | Property Loan [Member]
Maximum Exposure to Loss	3,383,615	3,564,755
Carrying Value	$ 3,383,615	$ 3,564,755