Accounting Policies (Schedule of Foreign Currency Transaction Gains and Losses) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounting Policies [Abstract]
Selling, general, and administrative expense	$ 4,127	$ (381)	$ (5,090)
Other (income)/expense, net	4,634	(3,532)	1,496
Total transaction (gains)/losses	8,761	(3,913)	(3,594)
Gain/(loss) on long-term intercompany loans	$ 1,867	$ 3,515	$ (5,225)