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Incentive Compensation - Additional Information (Details) - USD ($)
3 Months Ended 9 Months Ended
Mar. 18, 2019
Jan. 14, 2019
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]            
Stock-based compensation expense     $ 5,174,000 $ 4,330,000 $ 17,859,000 $ 15,245,000
Equity Incentive Plan [Member] | Full Value Awards [Member]            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]            
Shares available for grant     8,338,280   8,338,280  
2018 Performance Program [Member]            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]            
Performance measurement period, term   3 years        
Performance measurement period, start date   Jan. 01, 2019        
Performance measurement period, end date   Dec. 31, 2021        
Fair value of awards granted   $ 8,106,000        
Vesting period   4 years        
2018 Performance Program [Member] | Share-Based Compensation Award Tranche One [Member]            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]            
Percentage of the awards that vest   50.00%        
2018 Performance Program [Member] | Share-Based Compensation Award Tranche Two [Member]            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]            
Percentage of the awards that vest   50.00%        
2015 Performance Program [Member]            
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]            
Performance measurement period, units forfeited 1,109,358          
Fair value granted         $ 10,914,000  
Unrecognized compensation cost     $ 589,000   $ 589,000  
Unrecognized compensation cost expected to be recognized over a weighted-average period         6 months