Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016 USD ($) Customer Segment	Dec. 31, 2015 USD ($) Customer
Summary Of Significant Accounting Policies [Line Items]
Deferred revenue-current	$ 149,000	$ 554,000
Long-term deferred revenue	$ 100,000	$ 100,000
Number of major customers representing outstanding trade receivables | Customer	3	3
Life of inventory	2 years
Protracted length of inventory	1 year
Inventory valuation reserves	$ 200,000	$ 1,800,000
Estimated useful life of intangible assets	10 years
Number of reportable segments | Segment	1
Period of warranty	1 year
Warranty claim liability	$ 0	0
Other current assets	1,804,000	4,755,000
Other assets	4,148,000	2,579,000
Debt - current	6,934,000	2,956,000
Debt - non-current	$ 12,441,000	16,848,000
Accounting Standards Update 2015-03 | Scenario, Previously Reported
Summary Of Significant Accounting Policies [Line Items]
Other current assets		32,000
Other assets		36,000
Accounting Standards Update 2015-03 | Scenario, Adjustment
Summary Of Significant Accounting Policies [Line Items]
Other current assets		(32,000)
Other assets		(36,000)
Debt - current		(32,000)
Debt - non-current		$ (36,000)
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	46.00%	49.00%