Quarterly report pursuant to Section 13 or 15(d)

Balance Sheet Components - Additional Information (Details)

v3.10.0.1
Balance Sheet Components - Additional Information (Details)
3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2018
USD ($)
Sep. 30, 2017
USD ($)
Sep. 30, 2018
USD ($)
Customer
Sep. 30, 2017
USD ($)
Customer
Dec. 31, 2017
USD ($)
Customer
Schedule Of Balance Sheet Components [Line Items]          
Unbilled Receivables $ 937,000   $ 937,000   $ 1,470,000
Accounts receivable, net $ 34,250,000   $ 34,250,000   31,444,000
Percentage of Non-US revenue invoiced in Euros 77.20% 77.20% 76.70% 75.20%  
Noncurrent inventories expected to be realized or consumed $ 672,000   $ 672,000   644,000
Salvage value of expenditures for additions, improvements and replacements 0   0    
Repairs and maintenance expense 545,000 $ 463,000 1,734,000 $ 1,808,000  
Depreciation and amortization 2,380,000 2,835,000 7,592,000 9,004,000  
Impairments of long-lived assets 0 0 0 0  
Impairment of finite lived intangible assets 0 0 0 0  
Amortization of intangible assets 332,000 101,000 929,000 253,000  
Construction in Process and Computer Software or Development Cost          
Schedule Of Balance Sheet Components [Line Items]          
Depreciation and amortization 0 $ 0 0 $ 0  
Customer Concentration Risk | Customer One          
Schedule Of Balance Sheet Components [Line Items]          
Accounts receivable, net $ 13,207,000   $ 13,207,000   10,394,000
Customer Concentration Risk | Customer Two          
Schedule Of Balance Sheet Components [Line Items]          
Accounts receivable, net         $ 6,459,000
Sales Revenue, Net | Customer Concentration Risk          
Schedule Of Balance Sheet Components [Line Items]          
Number of customers | Customer     1 1  
Net Accounts Receivable | Customer Concentration Risk          
Schedule Of Balance Sheet Components [Line Items]          
Number of customers | Customer     1   2
Raw materials | Supplier Concentration Risk | Vendor one          
Schedule Of Balance Sheet Components [Line Items]          
Concentration risk, percentage     19.80% 19.90%  
Raw materials | Supplier Concentration Risk | Vendor two          
Schedule Of Balance Sheet Components [Line Items]          
Concentration risk, percentage     12.60% 13.90%  
Raw materials | Supplier Concentration Risk | Vendor three          
Schedule Of Balance Sheet Components [Line Items]          
Concentration risk, percentage     9.60% 9.70%