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Equity Incentive Programs (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]      
Shares of class A stock reserved for issuance 10,871,652    
Stock option exercise price floor of fair market value of class A common stock (percent) 100.00%    
Shares available for issuance 1,571,841    
Stock-based compensation charges $ 15,600,000 $ 16,400,000 $ 15,200,000
Total future compensation expense $ 15,900,000    
Stock Options      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period 4 years    
Total future compensation expense $ 0    
Restricted Stock and Restricted Stock Units (RSUs)      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period 3 years    
Total future compensation expense $ 15,900,000    
Estimated Future Expense in Year One      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Total future compensation expense 10,000,000    
Estimated Future Expense in Year One | Restricted Stock and Restricted Stock Units (RSUs)      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Total future compensation expense 10,000,000    
Estimated Future Expense in Year Two      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Total future compensation expense 5,200,000    
Estimated Future Expense in Year Two | Restricted Stock and Restricted Stock Units (RSUs)      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Total future compensation expense 5,200,000    
Estimated Future Expense in Year Three      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Total future compensation expense 700,000    
Estimated Future Expense in Year Three | Restricted Stock and Restricted Stock Units (RSUs)      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Total future compensation expense $ 700,000    
Minimum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period 3 years    
Maximum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period 4 years