Annual report pursuant to Section 13 and 15(d)

Share-Based Awards and Cash-Based Awards - Additional Information (Details)

v3.10.0.1
Share-Based Awards and Cash-Based Awards - Additional Information (Details) - USD ($)
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Share based compensation performance awards grant performance period 10 years    
Annual incentive awards payment period 90 days    
Common stock available for award under plans 11,852,592    
Recognized incentive compensation expense $ 3,540,000 $ 8,065,000 $ 11,013,000
Directors Compensation Plan      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Common stock available for award under plans 128,980    
Adjusted EBITDA and Adjusted EBITDA Margin      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Restricted stock units earning per share, minimum 0.00% 0.00% 0.00%
Restricted stock units earning per share, maximum 100.00% 100.00% 100.00%
Restricted Stock Units (RSUs)      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Common shares available for issuance reduced conversion basis one-for-one basis    
Shares granted, grant date fair value $ 6,800,000 $ 5,900,000 $ 9,300,000
Shares vested, vested date fair value 11,000,000 5,500,000 2,400,000
Unrecognized share-based compensation expense $ 6,400,000    
Recognition period for unrecognized compensation expense 2020-11    
Recognized incentive compensation expense $ 3,260,000 7,785,000 10,640,000
Restricted Shares      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Shares granted, grant date fair value 300,000 300,000 300,000
Shares vested, vested date fair value 700,000 100,000 100,000
Unrecognized share-based compensation expense $ 400,000    
Recognition period for unrecognized compensation expense 2021-04    
Recognized incentive compensation expense $ 280,000 $ 280,000 $ 373,000
Restricted Shares | Directors Compensation Plan Share-Based Awards      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Vesting rights description Vesting occurs upon completion of the specified vesting period and one-third of each grant vests each year over a three-year period.    
Grant vesting period 3 years 3 years 3 years
2017 Cash-based Awards | Minimum      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Adjusted EBITDA less interest expense $ 200,000,000    
2017 Annual Incentive Award Agreement      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Cash based award expected payment period 2018-03    
2018 Cash-based Awards      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Adjusted EBITDA less interest expense $ 200,000,000    
2018 Annual Incentive Award Agreement      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Cash based award expected payment period 2019-03    
2016 Cash-based Awards      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Recognized incentive compensation expense $ 0 $ 0 $ 0
2016 Cash-based Awards | Minimum      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Adjusted EBITDA less interest expense $ 300,000,000