Variable Interest Entities Property Asset Carrying Value and Maximum Exposure (Details)	Sep. 30, 2015 USD ($)
Mortgage revenue bonds [Member]
Maximum Exposure to Loss	$ 75,592,446
Carrying Value	83,214,487
Property Loan [Member]
Maximum Exposure to Loss	14,278,048
Carrying Value	7,920,299
Ashley Square [Member] | Mortgage revenue bonds [Member]
Maximum Exposure to Loss	5,114,000
Carrying Value	5,572,262
Ashley Square [Member] | Property Loan [Member]
Maximum Exposure to Loss	7,839,749
Carrying Value	1,482,000
Bruton Apts [Member] | Mortgage revenue bonds [Member]
Maximum Exposure to Loss	18,145,000
Carrying Value	19,648,516
Bruton Apts [Member] | Property Loan [Member]
Maximum Exposure to Loss	0
Carrying Value	0
Cross Creek [Member] | Mortgage revenue bonds [Member]
Maximum Exposure to Loss	6,095,463
Carrying Value	8,903,193
Cross Creek [Member] | Property Loan [Member]
Maximum Exposure to Loss	3,619,116
Carrying Value	3,619,116
Glenview Apts [Member] | Mortgage revenue bonds [Member]
Maximum Exposure to Loss	6,723,000
Carrying Value	6,850,865
Glenview Apts [Member] | Property Loan [Member]
Maximum Exposure to Loss	0
Carrying Value	0
Harden Ranch [Member] | Mortgage revenue bonds [Member]
Maximum Exposure to Loss	6,960,000
Carrying Value	7,531,277
Harden Ranch [Member] | Property Loan [Member]
Maximum Exposure to Loss	0
Carrying Value	0
Montclair Apts [Member] | Mortgage revenue bonds [Member]
Maximum Exposure to Loss	3,458,000
Carrying Value	3,529,444
Montclair Apts [Member] | Property Loan [Member]
Maximum Exposure to Loss	0
Carrying Value	0
Santa Fe Apts [Member] | Mortgage revenue bonds [Member]
Maximum Exposure to Loss	4,736,000
Carrying Value	4,867,300
Santa Fe Apts [Member] | Property Loan [Member]
Maximum Exposure to Loss	0
Carrying Value	0
Seasons at Simi Valley [Member] | Mortgage revenue bonds [Member]
Maximum Exposure to Loss	6,320,000
Carrying Value	6,539,709
Seasons at Simi Valley [Member] | Property Loan [Member]
Maximum Exposure to Loss	0
Carrying Value	0
Silver Moon [Member] | Mortgage revenue bonds [Member]
Maximum Exposure to Loss	7,995,983
Carrying Value	9,060,239
Silver Moon [Member] | Property Loan [Member]
Maximum Exposure to Loss	2,819,183
Carrying Value	2,819,183
Tyler Park Apartments [Member] | Mortgage revenue bonds [Member]
Maximum Exposure to Loss	6,075,000
Carrying Value	6,478,195
Tyler Park Apartments [Member] | Property Loan [Member]
Maximum Exposure to Loss	0
Carrying Value	0
Westside Village Market [Member] | Mortgage revenue bonds [Member]
Maximum Exposure to Loss	3,970,000
Carrying Value	4,233,487
Westside Village Market [Member] | Property Loan [Member]
Maximum Exposure to Loss	0
Carrying Value	$ 0