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Defined Contribution Plan - Additional Information (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Defined Contribution Plan Disclosure [Line Items]      
Defined contribution plan maximum annual compensation 100.00%    
Percentage of employee contribution of the salary 5.00%    
Defined contribution plan, contributions $ 4.4 $ 4.1 $ 4.0
Maximum      
Defined Contribution Plan Disclosure [Line Items]      
Percentage of employee contribution of the salary 3.00%    
3% of Employee Contribution      
Defined Contribution Plan Disclosure [Line Items]      
Percentage of employers matching contribution with employee contribution 100.00%    
5% of Employee Contribution      
Defined Contribution Plan Disclosure [Line Items]      
Percentage of employers matching contribution with employee contribution 50.00%