Preferred Equity Investments - Additional Information (Details)	3 Months Ended	9 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2017 USD ($)
Schedule Of Investments [Abstract]
Preferred equity ownership percentage	24.40%	24.40%
Valuation allowance on preferred equity investment	$ 19,588,000	$ 19,588,000