Segment and Geographical Information - Segment Reporting Information by Segment (Details) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||||
|---|---|---|---|---|---|---|
Sep. 30, 2017 |
Sep. 24, 2016 |
Sep. 30, 2017 |
Sep. 24, 2016 |
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| Segment Reporting Information [Line Items] | ||||||
| Revenue | [1] | $ 44,536 | $ 40,791 | $ 129,874 | $ 118,241 | |
| United States | ||||||
| Segment Reporting Information [Line Items] | ||||||
| Revenue | 40,344 | 37,293 | 118,522 | 107,993 | ||
| Non-US | ||||||
| Segment Reporting Information [Line Items] | ||||||
| Revenue | $ 4,192 | $ 3,498 | $ 11,352 | $ 10,248 | ||
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