Summary of Significant Accounting Policies - Additional Information (Detail)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017 USD ($) Customer	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) Customer Segment	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($) Customer
Summary Of Significant Accounting Policies [Line Items]
Number of major customers representing outstanding trade receivables | Customer	2		2		3
Life of inventory			2 years
Protracted length of inventory			1 year
Inventory valuation reserves	$ 200,000		$ 200,000		$ 200,000
Estimated useful life of intangible assets			10 years
Number of reportable segments | Segment			1
Impairment charges on long-lived assets	0	$ 0	$ 0	$ 0
Period of warranty			1 year
Warranty claim liability	$ 0		$ 0		$ 0
Minimum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of property and equipment			3 years
Maximum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of property and equipment			5 years
Trade Accounts Receivable | Customer Concentration Risk
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage			42.00%		46.00%