Balance Sheet Items - Allowances for Sales Returns and Chargebacks (Detail) - USD ($) $ in Thousands |
12 Months Ended | |
|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
|
| Movement in Valuation Allowances and Reserves [Roll Forward] | ||
| Balance, beginning of period | $ 232 | $ 294 |
| Less: deductions and other adjustments | 2,662 | 2,905 |
| Less: deductions and other adjustments | (2,675) | (2,967) |
| Balance, end of period | $ 219 | $ 232 |