Commitments and Contingencies Fair Market Value Table (Details) - USD ($)	6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Maximum Committed Amounts for 2017 through 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Purchase Commitment, Amount	$ 66,940,000
Maximum Committed Amounts for 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Purchase Commitment, Amount	9,850,000
Bond Purchase Commitment [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unrealized Gain	$ 17,218,819	$ 5,634,360
15 West Apartments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Forward Bond Commitment, Purchase Date	Jul. 01, 2014
Debt Instrument, Interest Rate, Stated Percentage	6.25%
15 West Apartments [Member] | Maximum Committed Amounts for 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Purchase Commitment, Amount	$ 9,850,000
15 West Apartments [Member] | Bond Purchase Commitment [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unrealized Gain	$ 2,031,956	945,009
Villas at Plano Gateway [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Forward Bond Commitment, Purchase Date	Dec. 01, 2014
Debt Instrument, Interest Rate, Stated Percentage	6.00%
Villas at Plano Gateway [Member] | Maximum Committed Amounts for 2017 through 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Purchase Commitment, Amount	$ 20,000,000
Villas at Plano Gateway [Member] | Bond Purchase Commitment [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unrealized Gain	$ 3,726,000	1,469,213
Palo Alto [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Forward Bond Commitment, Purchase Date	Jul. 01, 2015
Debt Instrument, Interest Rate, Stated Percentage	5.80%
Palo Alto [Member] | Maximum Committed Amounts for 2017 through 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Purchase Commitment, Amount	$ 19,540,000
Palo Alto [Member] | Bond Purchase Commitment [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unrealized Gain	$ 5,217,962	1,439,600
Village at River's Edge [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Forward Bond Commitment, Purchase Date	May 01, 2015
Debt Instrument, Interest Rate, Stated Percentage	6.00%
Village at River's Edge [Member] | Maximum Committed Amounts for 2017 through 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Purchase Commitment, Amount	$ 11,000,000
Village at River's Edge [Member] | Bond Purchase Commitment [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unrealized Gain	$ 2,083,950	636,560
Village at Avalon [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Forward Bond Commitment, Purchase Date	Nov. 01, 2015
Debt Instrument, Interest Rate, Stated Percentage	5.80%
Village at Avalon [Member] | Maximum Committed Amounts for 2017 through 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Purchase Commitment, Amount	$ 16,400,000
Village at Avalon [Member] | Bond Purchase Commitment [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unrealized Gain	$ 4,158,951	$ 1,143,978