Quarterly report pursuant to Section 13 or 15(d)

Balance Sheet Components - Additional Information (Details)

v3.19.1
Balance Sheet Components - Additional Information (Details)
3 Months Ended
Mar. 31, 2019
USD ($)
Customer
Mar. 31, 2018
USD ($)
Customer
Dec. 31, 2018
USD ($)
Schedule Of Balance Sheet Components [Line Items]      
Unbilled Receivables $ 560,000   $ 589,000
Accounts receivable, net $ 41,525,000   37,041,000
Percentage of Non-US revenue invoiced in Euros 72.50%    
Salvage value of expenditures for additions, improvements and replacements $ 0    
Repairs and maintenance expense 662,000 $ 560,000  
Depreciation and amortization 2,466,000 2,695,000  
Impairments of long-lived assets 0 0  
Impairment of finite lived intangible assets 0 0  
Amortization of intangible assets 328,000 298,000  
Construction in Process and Computer Software or Development Cost      
Schedule Of Balance Sheet Components [Line Items]      
Depreciation and amortization 0 0  
Other Noncurrent Assets      
Schedule Of Balance Sheet Components [Line Items]      
Noncurrent inventories expected to be realized or consumed 1,348,000   $ 1,085,000
Customer Concentration Risk | Customer One      
Schedule Of Balance Sheet Components [Line Items]      
Accounts receivable, net $ 18,615,000 16,198,000  
Customer Concentration Risk | Customer Two      
Schedule Of Balance Sheet Components [Line Items]      
Accounts receivable, net   $ 4,155,000  
Sales Revenue, Net | Customer Concentration Risk      
Schedule Of Balance Sheet Components [Line Items]      
Number of customers | Customer 0 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 20.60% 18.50%  
Raw materials | Supplier Concentration Risk | Vendor two      
Schedule Of Balance Sheet Components [Line Items]      
Concentration risk, percentage 11.60% 15.10%  
Raw materials | Supplier Concentration Risk | Vendor three      
Schedule Of Balance Sheet Components [Line Items]      
Concentration risk, percentage 11.40% 12.00%