Stock Plans and Stock-Based Compensation - Estimated Weighted-Average Grant Date Fair Value (Detail) - $ / shares |
12 Months Ended | |
|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
|
| Options [Member] | ||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||
| Expected term | 6 years 1 month 6 days | 6 years 1 month 6 days |
| Expected volatility | 80.00% | 78.00% |
| Risk-free interest rate | 1.57% | 1.65% |
| Expected dividend yield | 0.00% | 0.00% |
| Weighted-average grant date fair value per share | $ 0.89 | $ 6.13 |
| Performance Option [Member] | ||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||
| Expected term | 5 years 1 month 6 days | 0 years |
| Expected volatility | 85.00% | |
| Risk-free interest rate | 1.56% | |
| Expected dividend yield | 0.00% | 0.00% |
| Weighted-average grant date fair value per share | $ 1.20 | |
| X | ||||||||||
- Definition Agreed-upon price for the exchange of the underlying asset relating to the share-based payment award. No definition available.
|
| X | ||||||||||
- Definition The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition The risk-free interest rate assumption that is used in valuing an option on its own shares. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
|
| X | ||||||||||
- Definition Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Details
|
| X | ||||||||||
- Details
|