Commitments and Contingencies Fair Market Value Table (Details) - USD ($)	6 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Bond Purchase Commitments - Fair Value	$ 3,165,172	$ 2,399,449
Maximum Committed Amounts for 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Purchase Commitment, Amount	11,000,000
Maximum Committed Amounts for 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Purchase Commitment, Amount	$ 35,940,000
Villas at Plano Gateway [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Forward Bond Commitment, Purchase Date	Dec. 31, 2014
Debt Instrument, Interest Rate, Stated Percentage	6.00%
Bond Purchase Commitments - Fair Value		838,200
Village at River's Edge [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Forward Bond Commitment, Purchase Date	May 31, 2015
Debt Instrument, Interest Rate, Stated Percentage	6.00%
Bond Purchase Commitments - Fair Value	$ 850,437	467,720
Village at River's Edge [Member] | Maximum Committed Amounts for 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Purchase Commitment, Amount	$ 11,000,000
Palo Alto [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Forward Bond Commitment, Purchase Date	Jul. 31, 2015
Debt Instrument, Interest Rate, Stated Percentage	5.80%
Bond Purchase Commitments - Fair Value	$ 1,207,209	627,429
Palo Alto [Member] | Maximum Committed Amounts for 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Purchase Commitment, Amount	$ 19,540,000
Village at Avalon [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Forward Bond Commitment, Purchase Date	Nov. 30, 2015
Debt Instrument, Interest Rate, Stated Percentage	5.80%
Bond Purchase Commitments - Fair Value	$ 1,107,526	$ 466,100
Village at Avalon [Member] | Maximum Committed Amounts for 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Purchase Commitment, Amount	$ 16,400,000