Commitments and Contingencies Fair Market Value Table (Details) - USD ($)	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unrealized Gain	$ 3,080,857		$ 5,082,559
Long-term Purchase Commitment, Amount	$ 42,665,912	$ 0
Silver Moon [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.00%
Long-term Purchase Commitment, Amount	$ 8,000,000
Forward Bond Commitment, Purchase Date	Jun. 01, 2013
15 West Apartments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.25%
Long-term Purchase Commitment, Amount	$ 9,900,000
Forward Bond Commitment, Purchase Date	Jul. 01, 2014
Palo Alto [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.80%
Long-term Purchase Commitment, Amount	$ 19,540,000
Forward Bond Commitment, Purchase Date	Jul. 01, 2015
Villas at Plano Gateway [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.00%
Long-term Purchase Commitment, Amount	$ 20,000,000
Forward Bond Commitment, Purchase Date	Dec. 01, 2014
Village at River's Edge [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.00%
Long-term Purchase Commitment, Amount	$ 8,720,000
Forward Bond Commitment, Purchase Date	May 01, 2015
Vantage at Harlingen [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.00%
Unrealized Gain			707,813
Long-term Purchase Commitment, Amount	$ 18,000,000
Forward Bond Commitment, Purchase Date	Aug. 01, 2013
Vantage at Judson [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.00%
Unrealized Gain			717,230
Long-term Purchase Commitment, Amount	$ 26,700,000
Forward Bond Commitment, Purchase Date	Dec. 01, 2012
Bond Purchase Commitment [Member] | Silver Moon [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unrealized Gain	$ 0		413,600
Bond Purchase Commitment [Member] | 15 West Apartments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unrealized Gain	785,932		809,178
Bond Purchase Commitment [Member] | Palo Alto [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unrealized Gain	959,023		0
Bond Purchase Commitment [Member] | Villas at Plano Gateway [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unrealized Gain	1,103,000		1,133,400
Bond Purchase Commitment [Member] | Village at River's Edge [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unrealized Gain	487,971		0
Bond Purchase Commitment [Member] | Vantage at Harlingen [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unrealized Gain	0		1,433,700
Bond Purchase Commitment [Member] | Vantage at Judson [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unrealized Gain	$ 0		$ 1,990,535