Quarterly report pursuant to Section 13 or 15(d)

Debt - Schedule of Debt (Details)

v3.19.1
Debt - Schedule of Debt (Details) - USD ($)
$ in Thousands
Mar. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Debt Instrument [Line Items]      
Carrying value $ 300,957    
Term Loan      
Debt Instrument [Line Items]      
Principal outstanding 113,457 $ 114,990  
Unamortized discount (157) (171)  
Unamortized debt issuance costs (125) (137)  
Carrying value 113,175 114,682  
Term Loan | Delayed Draw Term Loan      
Debt Instrument [Line Items]      
Principal outstanding 187,500 190,000  
Unamortized discount (553) (606)  
Unamortized debt issuance costs (330) (361)  
Carrying value $ 186,617 $ 189,033 $ 200,000