Variable Interest Entities Property Asset Carrying Value and Maximum Exposure (Details) - USD ($)	Mar. 31, 2016	Dec. 31, 2015
Available-for-sale Securities [Member]
Available for Sale Security and Property Loan Receivable, Carrying Value	$ 115,579,404	$ 111,052,042
Available for Sale Security and Property Loan Receivable, Maximum Exposure	109,262,999	103,483,793
Property Loan [Member]
Available for Sale Security and Property Loan Receivable, Carrying Value	15,467,694	13,004,505
Available for Sale Security and Property Loan Receivable, Maximum Exposure	19,064,036	19,464,977
Ashley Square [Member] | Available-for-sale Securities [Member]
Available for Sale Security and Property Loan Receivable, Carrying Value	5,600,695	5,607,163
Available for Sale Security and Property Loan Receivable, Maximum Exposure	5,084,000	5,099,000
Ashley Square [Member] | Property Loan [Member]
Available for Sale Security and Property Loan Receivable, Carrying Value	1,482,000	1,482,000
Available for Sale Security and Property Loan Receivable, Maximum Exposure	5,078,342	7,942,472
Bridle Ridge [Member] | Available-for-sale Securities [Member]
Available for Sale Security and Property Loan Receivable, Carrying Value	8,552,233
Available for Sale Security and Property Loan Receivable, Maximum Exposure	7,565,000
Bruton Apts [Member] | Available-for-sale Securities [Member]
Available for Sale Security and Property Loan Receivable, Carrying Value	20,454,301	20,046,839
Available for Sale Security and Property Loan Receivable, Maximum Exposure	18,145,000	18,145,000
Columbia Gardens [Member] | Available-for-sale Securities [Member]
Available for Sale Security and Property Loan Receivable, Carrying Value	14,915,592	15,224,597
Available for Sale Security and Property Loan Receivable, Maximum Exposure	15,222,003	15,224,597
Cross Creek [Member] | Available-for-sale Securities [Member]
Available for Sale Security and Property Loan Receivable, Carrying Value		9,034,294
Available for Sale Security and Property Loan Receivable, Maximum Exposure		6,101,605
Cross Creek [Member] | Property Loan [Member]
Available for Sale Security and Property Loan Receivable, Carrying Value		3,624,614
Available for Sale Security and Property Loan Receivable, Maximum Exposure		3,624,614
Glenview Apts [Member] | Available-for-sale Securities [Member]
Available for Sale Security and Property Loan Receivable, Carrying Value	6,829,007	6,926,243
Available for Sale Security and Property Loan Receivable, Maximum Exposure	6,723,000	6,723,000
Harden Ranch [Member] | Available-for-sale Securities [Member]
Available for Sale Security and Property Loan Receivable, Carrying Value	7,725,305	7,628,981
Available for Sale Security and Property Loan Receivable, Maximum Exposure	6,960,000	6,960,000
Montclair Apts [Member] | Available-for-sale Securities [Member]
Available for Sale Security and Property Loan Receivable, Carrying Value	3,582,096	3,569,573
Available for Sale Security and Property Loan Receivable, Maximum Exposure	3,458,000	3,458,000
Santa Fe Apts [Member] | Available-for-sale Securities [Member]
Available for Sale Security and Property Loan Receivable, Carrying Value	4,933,037	4,884,102
Available for Sale Security and Property Loan Receivable, Maximum Exposure	4,736,000	4,736,000
Seasons at Simi Valley [Member] | Available-for-sale Securities [Member]
Available for Sale Security and Property Loan Receivable, Carrying Value	6,803,653	6,724,110
Available for Sale Security and Property Loan Receivable, Maximum Exposure	6,320,000	6,320,000
Sycamore Walk [Member] | Available-for-sale Securities [Member]
Available for Sale Security and Property Loan Receivable, Carrying Value	5,493,352	5,447,000
Available for Sale Security and Property Loan Receivable, Maximum Exposure	5,447,000	5,447,000
Tyler Park Apartments [Member] | Available-for-sale Securities [Member]
Available for Sale Security and Property Loan Receivable, Carrying Value	6,636,002	6,562,209
Available for Sale Security and Property Loan Receivable, Maximum Exposure	6,065,947	6,075,000
Vantage at Braunfels LLC [Member] | Property Loan [Member]
Available for Sale Security and Property Loan Receivable, Carrying Value	6,578,789	4,364,787
Available for Sale Security and Property Loan Receivable, Maximum Exposure	6,578,789	4,364,787
Vantage at Brooks LLC [Member] | Property Loan [Member]
Available for Sale Security and Property Loan Receivable, Carrying Value	7,406,905	3,533,104
Available for Sale Security and Property Loan Receivable, Maximum Exposure	7,406,905	3,533,104
Westside Village Market [Member] | Available-for-sale Securities [Member]
Available for Sale Security and Property Loan Receivable, Carrying Value	4,220,252	4,172,340
Available for Sale Security and Property Loan Receivable, Maximum Exposure	3,964,084	3,970,000
Willow Run [Member] | Available-for-sale Securities [Member]
Available for Sale Security and Property Loan Receivable, Carrying Value	14,916,596	15,224,591
Available for Sale Security and Property Loan Receivable, Maximum Exposure	15,221,965	$ 15,224,591
Woodlynn Village [Member] | Available-for-sale Securities [Member]
Available for Sale Security and Property Loan Receivable, Carrying Value	4,917,283
Available for Sale Security and Property Loan Receivable, Maximum Exposure	$ 4,351,000