Quarterly report pursuant to Section 13 or 15(d)

Share-Based Compensation and Cash-Based Incentive Compensation - Additional Information (Details)

v3.8.0.1
Share-Based Compensation and Cash-Based Incentive Compensation - Additional Information (Details) - USD ($)
3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Common stock available for award under plans 13,363,792  
Recognized incentive compensation expense $ 1,219,000 $ 1,928,000
Restricted Stock Units (RSUs)    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Shares granted 0  
Shares vested 0  
Unrecognized share-based compensation expense $ 5,000,000  
Recognition period for unrecognized compensation expense 2019-11  
Recognized incentive compensation expense $ 1,149,000 1,858,000
Restricted Shares    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Shares granted 0  
Shares vested 0  
Unrecognized share-based compensation expense $ 300,000  
Recognition period for unrecognized compensation expense 2020-04  
Recognized incentive compensation expense $ 70,000 70,000
2017 Cash-based Awards    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Cash based award expected payment period 2018-03  
2017 Cash-based Awards | Minimum    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Adjusted EBITDA less interest expense $ 200,000,000  
2016 Cash-based Awards    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Recognized incentive compensation expense $ 0 $ 0
Cash based compensation payment period after achievement of financial condition 30 days  
2016 Cash-based Awards | Minimum    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Adjusted EBITDA less interest expense $ 300,000,000  
Amended and Restated Incentive Compensation Plan    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Amendment increased the number of shares available in the Plan 7,700,000  
Directors Compensation Plan    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Common stock available for award under plans 170,524