Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Beginning of year	$ (17,832)
End of year	(33,650)	$ (17,832)
Accumulated Translation Adjustment [Member]
Beginning of year	(17,869)	(57,965)	$ (48,091)
Translation adjustments	(15,917)	40,096	(9,874)
End of year	(33,786)	(17,869)	(57,965)
Accumulated Defined Benefit Plans Net Derivative Instruments [Member]
Beginning of year	37	(17)
Net derivative instrument gain (loss), net of tax	99	54	(17)
End of year	$ 136	$ 37	$ (17)