Commitments and Contingencies - Summary of Bond Purchase Commitments (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Long-term Purchase Commitment [Line Items]
Bond Purchase Commitments, Fair Value	$ 2,027,473	$ 3,002,540
Bond Purchase Commitments, Maximum Committed Amounts for 2018	$ 35,940,000
Palo Alto [Member]
Long-term Purchase Commitment [Line Items]
Bond Purchase Commitments, Commitment Date	Jul. 31, 2015
Bond Purchase Commitments, Rate	5.80%
Bond Purchase Commitments, Fair Value	$ 1,086,144	1,616,143
Bond Purchase Commitments, Maximum Committed Amounts for 2018	$ 19,540,000
Village at Avalon [Member]
Long-term Purchase Commitment [Line Items]
Bond Purchase Commitments, Commitment Date	Nov. 30, 2015
Bond Purchase Commitments, Rate	5.80%
Bond Purchase Commitments, Fair Value	$ 941,329	$ 1,386,397
Bond Purchase Commitments, Maximum Committed Amounts for 2018	$ 16,400,000