Quarterly report pursuant to Section 13 or 15(d)

Balance Sheet Components - Summary of Changes in Net Carrying Values of Intangible Assets (Details)

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Balance Sheet Components - Summary of Changes in Net Carrying Values of Intangible Assets (Details) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Mar. 31, 2019
Dec. 31, 2018
Finite Lived Intangible Assets [Line Items]    
Gross carrying amount $ 6,552 $ 6,584
Accumulated amortization 3,141 2,829
Net amount $ 3,411 $ 3,755
Licenses    
Finite Lived Intangible Assets [Line Items]    
Average estimated useful lives (in years) 10 years 10 years
Gross carrying amount $ 185 $ 185
Accumulated amortization 158 155
Net amount $ 27 $ 30
Patents And Websites    
Finite Lived Intangible Assets [Line Items]    
Average estimated useful lives (in years) 5 years 5 years
Gross carrying amount $ 4,164 $ 4,164
Accumulated amortization 1,808 1,640
Net amount $ 2,356 $ 2,524
Customer Relationships    
Finite Lived Intangible Assets [Line Items]    
Average estimated useful lives (in years) 4 years 4 years
Gross carrying amount $ 1,346 $ 1,373
Accumulated amortization 645 572
Net amount $ 701 $ 801
Non-Compete Agreement    
Finite Lived Intangible Assets [Line Items]    
Average estimated useful lives (in years) 2 years 3 months 18 days 2 years 3 months 18 days
Gross carrying amount $ 224 $ 229
Accumulated amortization 182 154
Net amount 42 75
Commercials    
Finite Lived Intangible Assets [Line Items]    
Gross carrying amount 633 633
Accumulated amortization 348 308
Net amount $ 285 $ 325
Commercials | Minimum    
Finite Lived Intangible Assets [Line Items]    
Average estimated useful lives (in years) 2 years 2 years
Commercials | Maximum    
Finite Lived Intangible Assets [Line Items]    
Average estimated useful lives (in years) 3 years 3 years