Balance Sheet Components (Accrued liabilities) (Details) - USD ($) $ in Thousands |
Dec. 31, 2018 |
Dec. 31, 2017 |
|---|---|---|
| Accrued liabilities | ||
| Sales returns and current portion of warranty liability | $ 2,539 | $ 2,872 |
| Compensation accruals | 5,444 | 5,241 |
| Other accrued liabilities | 1,159 | 2,722 |
| Total accrued liabilities | $ 9,142 | $ 10,835 |