Stockholders' Equity (Deficit) - Schedule of Fair Value Assumptions (Detail) |
9 Months Ended | 12 Months Ended | |
|---|---|---|---|
Sep. 30, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
| Expected volatility | 65.00% | 55.00% | |
| Risk-free interest rate, minimum | 1.89% | 1.30% | 1.34% |
| Risk-free interest rate, maximum | 2.20% | 1.72% | 2.07% |
| Expected dividend yield | 0.00% | 0.00% | 0.00% |
| Minimum [Member] | |||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
| Expected terms (in years) | 5 years 9 months 29 days | 5 years 6 months 29 days | 5 years 3 months 11 days |
| Expected volatility | 55.00% | ||
| Maximum [Member] | |||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
| Expected terms (in years) | 6 years 29 days | 6 years 29 days | 6 years 26 days |
| Expected volatility | 60.00% | ||
| 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 maximum risk-free interest rate assumption that is used in valuing an option on its own shares. No definition available.
|
| X | ||||||||||
- Definition The minimum risk-free interest rate assumption that is used in valuing an option on its own shares. No definition available.
|
| 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
|