Summary of Significant Accounting Policies - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2016 USD ($) Segment	Dec. 31, 2015 USD ($)
Summary Of Significant Accounting Policy [Line Items]
Number of operating segment | Segment	1
Minimum [Member] | Property Plant and Equipment Other than Leasehold Improvement [Member]
Summary Of Significant Accounting Policy [Line Items]
Estimated useful lives of assets	3 years
Maximum [Member] | Property Plant and Equipment Other than Leasehold Improvement [Member]
Summary Of Significant Accounting Policy [Line Items]
Estimated useful lives of assets	5 years
Other Assets [Member]
Summary Of Significant Accounting Policy [Line Items]
Long-term portion of restricted cash	$ 200,000	$ 200,000
Prepaid Expenses and Other Current Assets [Member]
Summary Of Significant Accounting Policy [Line Items]
Current portion of restricted cash	$ 12,000	$ 25,000