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Stock-based Compensation - Performance Share Unit Awards - Assumptions (Details) - Performance Share Unit Awards
9 Months Ended
Sep. 30, 2017
Stock-based Compensation  
Forecast period (years) 2 years 8 months 16 days
Risk-free interest rate (as a percent) 1.34%
Jones stock price volatility (as a percent) 78.93%
Expected percentage of performance share units earned (as a percent) 29.00%