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Capital Stock and Equity Compensation (Additional Information) (Details)
3 Months Ended 9 Months Ended 90 Months Ended
Sep. 30, 2019
USD ($)
Sep. 30, 2018
USD ($)
Sep. 30, 2019
USD ($)
offering_periods
Sep. 30, 2018
USD ($)
Sep. 30, 2019
shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Proceeds from the exercise of stock options, net     $ 344,000 $ 734,000  
Performance-Based Restricted Stock Units          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Restricted stock award program, measurement period (years)     3 years    
Expected dividend yield (percent)     0.00%    
Compensation expense $ 1,500,000 $ 1,300,000 $ 3,500,000 3,100,000  
Performance-Based Restricted Stock Units | Minimum          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Restricted stock award program, awarded shares as a percentage of the original award amount (percent)     0.00%    
Performance-Based Restricted Stock Units | Maximum          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Restricted stock award program, awarded shares as a percentage of the original award amount (percent)     200.00%    
Deferred Stock Units          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Compensation expense 1,100,000 900,000 $ 0 0  
Conversion ratio     1    
Time-Based Restricted Stock Units          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Compensation expense $ 1,500,000 $ 1,400,000 $ 4,400,000 $ 4,200,000  
Employee Stock Option          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Stock options, contractual term (years)     10 years    
Stock options, number of shares granted in period, gross | shares         0
Proceeds from the exercise of stock options, net     $ 1,600,000    
Options exercised, total intrinsic value     $ 300,000    
Employee Stock Purchase Plan          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Employee stock purchase plan, number of offering (offering period) | offering_periods     2    
Employee stock purchase plan, offering period (months)     6 months    
Employee stock purchase plan, purchase price discount (percent)     15.00%