| Stock Incentive Plan - Summary of Weighted-Average Assumptions Used for Options Granted (Details) | 9 Months Ended | |
|---|---|---|
| Sep. 30, 2017 | Sep. 30, 2016 | |
| Weighted-average assumptions | ||
| Expected term | 6 years 1 month 28 days | 4 years | 
| Expected volatility (as a percent) | 50.72% | 61.71% | 
| Risk free rate (as a percent) | 2.07% | 1.22% | 
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- References No definition available. 
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- 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 
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- 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 
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- 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 
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