Accounts Receivable and Sales Concentrations (Tables)

12 Months Ended

Dec. 31, 2018

Receivables [Abstract]

Summary of Accounts Receivables

Accounts receivable, net are comprised of the following amounts:

	As of December 31,
	2018		2017
Trade	$	135,260	$	110,165
Less—allowance for doubtful accounts	1,839		1,719
Accounts receivable, net	$	133,421	$	108,446

Summary of Activity in the Allowance for Doubtful Accounts

The following table presents activity in the allowance for doubtful accounts.

	Year Ended December 31,
	2018			2017			2016
Balance at beginning of year	$	1,719		$	1,069		$	1,055
Additions	754			648			153
Write-offs	(584		)	(101		)	(59		)
Currency impact	(50		)	103			(80		)
Balance at end of year	$	1,839		$	1,719		$	1,069