Segment Reporting - Schedule of Revenue by Geographic Segments (Detail) - USD ($) $ in Thousands |
3 Months Ended | |
|---|---|---|
Mar. 31, 2018 |
Mar. 31, 2017 |
|
| Segment Reporting Information [Line Items] | ||
| Total | $ 56,683 | $ 52,465 |
| % of Total | 100.00% | 100.00% |
| United States [Member] | ||
| Segment Reporting Information [Line Items] | ||
| Total | $ 24,823 | $ 23,597 |
| % of Total | 43.80% | 45.00% |
| Japan [Member] | ||
| Segment Reporting Information [Line Items] | ||
| Total | $ 11,652 | $ 14,461 |
| % of Total | 20.50% | 27.60% |
| Europe Middle East Africa [Member] | ||
| Segment Reporting Information [Line Items] | ||
| Total | $ 15,066 | $ 10,860 |
| % of Total | 26.60% | 20.70% |
| Rest of the World [Member] | ||
| Segment Reporting Information [Line Items] | ||
| Total | $ 5,142 | $ 3,547 |
| % of Total | 9.10% | 6.70% |