Organization and Basis of Presentation - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Organization And Basis Of Presentation [Line Items]
Notes payable to affiliates	$ 15,346,000		$ 14,893,000
Notes payable maturity	2018
Credit facilities and project related loans scheduled to mature during the remainder of 2018	$ 29,391,000
Reclassification of cash and restricted cash	(748,000)	$ (1,778,000)
Accounting Standards Update 2016-15 [Member]
Organization And Basis Of Presentation [Line Items]
Reclassification of cash and restricted cash	1,200,000	$ 1,500,000
Comstock Asset Management, L.C. [Member]
Organization And Basis Of Presentation [Line Items]
Fixed annual payment	1,000,000
Aggregate deposit	$ 2,500,000