Fair Value of Financial Instruments - Additional Information (Detail) $ in Thousands		9 Months Ended		12 Months Ended
	Jun. 30, 2017	Sep. 30, 2017 USD ($) Property		Dec. 31, 2016 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets Fair Value Disclosure		$ 93		$ 206
Significant Unobservable Inputs (Level 3)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Volatility rate		85.00%		51.00%
Credit adjusted discount rate		12.50%		10.00%
Dividend rate		18.90%		10.00%
Significant Unobservable Inputs (Level 3) | Non-Recurring Fair Value Measurements | Broker’s Opinion
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Discount rate	11.60%
Assets Fair Value Disclosure		$ 33,411
Number real estate asset | Property		1
Terminal capitalization rate	7.25%
Significant Unobservable Inputs (Level 3) | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Discount rate		15.50%		11.50%
Significant Unobservable Inputs (Level 3) | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Discount rate		15.80%		11.80%
Significant Other Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets Fair Value Disclosure		$ 93	[1]	$ 206	[2]
Significant Other Observable Inputs (Level 2) | Non-Recurring Fair Value Measurements | Letter of Intent
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets Fair Value Disclosure		$ 80,000
Number real estate asset | Property		3

[1] During the nine months ended September 30, 2017, there were no transfers between Level 1 and Level 2, and there were no transfers into and/or out of Level 3.

[2] During the year ended December 31, 2016, there were no transfers between Level 1 and Level 2, and there were no transfers into and/or out of Level 3.