Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Accounts Receivable (Details)

v3.19.3
Summary of Significant Accounting Policies - Accounts Receivable (Details) - USD ($)
$ in Thousands
Sep. 30, 2019
Dec. 31, 2018
Dec. 31, 2017
Accounts Receivable, after Allowance for Credit Loss, Current [Abstract]      
Customer receivables $ 75,108 $ 64,180 $ 60,400
Other receivables 1,033 1,466  
Rebates receivable 1,948 3,017  
Allowance for doubtful accounts (2,737) (2,228)  
Total $ 75,352 $ 66,435