Other (Income) Expense Foreign Currency Gain Loss by Currency (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Foreign Currency Transaction Gain (Loss), before Tax	$ 916	$ 1,832	$ 4,507
British Pound [Member]
Foreign Currency Transaction Gain (Loss), before Tax	92	(807)	(434)
Canadian Dollar [Member]
Foreign Currency Transaction Gain (Loss), before Tax	95	137	(1,848)
Euro [Member]
Foreign Currency Transaction Gain (Loss), before Tax	(1,413)	49	908
Indonesian Rupiah [Member] [Member]
Foreign Currency Transaction Gain (Loss), before Tax	(78)	(37)	(315)
Russian Ruble [Member]
Foreign Currency Transaction Gain (Loss), before Tax	161	(160)	45
Other Currencies Net [Member]
Foreign Currency Transaction Gain (Loss), before Tax	$ 227	$ (1,014)	$ (2,863)