Other (Income) Expense, Net (Foreign Currency (Gain) Loss by Currency) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Foreign exchange	$ 1,135	$ 139	$ 2,221	$ 707
Angolan Kwanza
Foreign exchange	33	(2)	194	(6)
Australian Dollar
Foreign exchange	50	(13)	161	0
British Pound
Foreign exchange	89	(27)	65	(82)
Canadian Dollar
Foreign exchange	(113)	(119)	244	(82)
Euro
Foreign exchange	108	431	92	1,266
Indonesian Rupiah
Foreign exchange	206	54	384	29
Turkish Lira
Foreign exchange	172	(7)	300	0
Other currencies, net
Foreign exchange	$ 590	$ (178)	$ 781	$ (418)