Segment and Geographical Information - Segment Reporting Information by Segment (Details) - USD ($) $ in Thousands |
3 Months Ended | |||
|---|---|---|---|---|
Mar. 31, 2018 |
Apr. 01, 2017 |
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| Segment Reporting Information [Line Items] | ||||
| Revenue | [1] | $ 47,325 | $ 43,366 | |
| United States | ||||
| Segment Reporting Information [Line Items] | ||||
| Revenue | 42,537 | 39,842 | ||
| Non-US | ||||
| Segment Reporting Information [Line Items] | ||||
| Revenue | $ 4,788 | $ 3,524 | ||
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