Stock Based Compensation - Schedule of Stock Based Compensation Expense (Detail) - USD ($) $ in Thousands |
3 Months Ended | |
|---|---|---|
Mar. 31, 2018 |
Mar. 31, 2017 |
|
| Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | ||
| Stock based compensation, Total expensed | $ 4,247 | $ 4,831 |
| Property and equipment | 14 | 22 |
| Total stock based compensation | 4,261 | 4,853 |
| Marketing and Selling [Member] | ||
| Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | ||
| Stock based compensation, Total expensed | 1,734 | 2,330 |
| Research and Development [Member] | ||
| Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | ||
| Stock based compensation, Total expensed | 988 | 1,018 |
| General and Administrative [Member] | ||
| Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] | ||
| Stock based compensation, Total expensed | $ 1,525 | $ 1,483 |