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Stock-Based Compensation - Restricted Stock Unit Activity (Details) - $ / shares
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Restricted stock units (RSUs)      
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]      
Unvested, beginning (in shares) 422,720    
Granted (in shares) 745,498    
Forfeited (in shares) (41,363)    
Vested (in shares) (255,873)    
Unvested, ending (in shares) 870,982 422,720  
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]      
Unvested, beginning - weighted average grant date fair value (in USD per share) $ 26.15    
Granted - weighted average grant date fair value (in USD per share) 6.51 $ 15.02 $ 50.10
Forfeited - weighted average grant date fair value (in USD per share) 31.50    
Vested - weighted average grant date fair value (in USD per share) 16.69    
Unvested, ending - weighted average grant date fair value (in USD per share) $ 11.88 $ 26.15  
Performance stock units      
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]      
Granted (in shares) 470,886