Debt - Component of Long Term Debt (Details) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2019
Jun. 30, 2019
Dec. 31, 2018
Jul. 01, 2019
Debt        
Principal outstanding $ 280,000 $ 280,000 $ 280,000  
Unamortized debt issuance costs (6,992) (6,992) (7,629)  
Unamortized debt discount (3,221) (3,221) (3,514)  
Long-term debt $ 269,787 $ 269,787 $ 268,857  
Average effective interest rate (as a percent) 5.95% 6.08%    
Effective interest rate (as a percent) 7.91% 7.91% 6.22%  
Term Loans        
Debt        
Principal amount       $ 1,100,000
Annual amortization percentage     1.00%  
Repayments of debt   $ 0 $ 80,000  
Due February 2025        
Debt        
Principal outstanding $ 280,000 $ 280,000 $ 280,000