Revenues Based on Customer Location (Detail) - USD ($) $ in Thousands |
12 Months Ended | |||||
|---|---|---|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
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| Segment Reporting Information [Line Items] | ||||||
| Total revenues | $ 72,653 | $ 59,499 | $ 50,808 | |||
| United States | ||||||
| Segment Reporting Information [Line Items] | ||||||
| Total revenues | 9,134 | 9,737 | 11,671 | |||
| Europe, Middle East | ||||||
| Segment Reporting Information [Line Items] | ||||||
| Total revenues | 10,901 | 7,064 | 5,655 | |||
| Asia Pacific | ||||||
| Segment Reporting Information [Line Items] | ||||||
| Total revenues | 52,618 | 42,698 | 33,482 | |||
| China | ||||||
| Segment Reporting Information [Line Items] | ||||||
| Total revenues | 30,030 | 29,982 | 20,568 | |||
| S. Korea | ||||||
| Segment Reporting Information [Line Items] | ||||||
| Total revenues | $ 15,512 | $ 6,173 | $ 0 | [1] | ||
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