Restructuring (Schedule of Restructuring Reserve by Type of Cost) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restructuring Reserve [Roll Forward]
Restructuring Reserve	$ 12,311	$ 10,010
Charges	6,128	29,503	$ 14,998
Cash payments	(13,592)	(21,806)
Non-cash adjustments	(3,583)	(5,303)
Currency translation	(28)	(93)
Restructuring Reserve	1,236	12,311	10,010
Employee Severance [Member]
Restructuring Reserve [Roll Forward]
Restructuring Reserve	12,106	9,498
Charges	2,543	23,557
Cash payments	(13,440)	(20,871)
Non-cash adjustments	2	12
Currency translation	1	(90)
Restructuring Reserve	1,212	12,106	9,498
Other Restructuring [Member]
Restructuring Reserve [Roll Forward]
Restructuring Reserve	205	512
Charges	3,585	5,946
Cash payments	(152)	(935)
Non-cash adjustments	(3,585)	(5,315)
Currency translation	(29)	(3)
Restructuring Reserve	$ 24	$ 205	$ 512