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Stock-based Compensation - Performance Unit Awards - Assumptions (Details) - Performance Unit Awards
9 Months Ended
Sep. 30, 2017
$ / shares
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 payout per unit as of the grant date (in dollars per share) $ 28.25