Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Accounts Receivable (Details)

v3.19.2
Summary of Significant Accounting Policies - Accounts Receivable (Details) - USD ($)
$ in Thousands
Jun. 30, 2019
Dec. 31, 2018
Dec. 31, 2017
Accounts Receivable, Net, Current [Abstract]      
Customer receivables $ 77,074 $ 64,180 $ 60,400
Other receivables 1,451 1,466  
Rebates receivable 1,948 3,017  
Allowance for doubtful accounts (2,627) (2,228)  
Total $ 77,846 $ 66,435