Summary of Significant Accounting Policies - Accounts Receivable, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Customer receivables	$ 64,180	$ 59,263
Other receivables	1,466	1,319
Rebates receivable	3,017	1,442
Allowance for doubtful accounts	(2,228)	(1,665)
Accounts receivable, net	$ 66,435	$ 60,359