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Capital Stock and Equity Compensation (Additional Information) (Details)
3 Months Ended 84 Months Ended
Mar. 31, 2019
USD ($)
offering_periods
Mar. 31, 2018
USD ($)
Mar. 31, 2019
shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Proceeds from the exercise of stock options, net $ 285,000 $ 473,000  
Deferred Stock Units      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Compensation expense $ 0 0  
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 $ 900,000    
Options exercised, total intrinsic value $ 300,000    
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 $ 900,000 1,000,000  
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%    
Time Based Restricted Stock      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Compensation expense $ 1,500,000 $ 1,500,000  
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%