Supplemental Information - Schedule of Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allowance For Doubtful Accounts Receivable Rollforward
Balance at beginning of period	$ 3,853	$ 2,591	$ 2,138
Bad debt expense	2,480	1,480	1,089
Write-offs, net of recoveries	(1,027)	(219)	(635)
Effect of foreign currency translation	(22)	1	(1)
Balance at end of period	$ 5,284	$ 3,853	$ 2,591