Goodwill and Other Intangible Assets (Schedule of intangible assets subject to amortization) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Finite-lived Intangible Assets [Roll Forward]
Intangible assets subject to amortization, beginning balance	$ 247,559	$ 254,459
Intangible assets acquired during the year	47,368	3,175
Amortization during the year	(30,745)	(34,279)	$ (39,545)
Currency translation during the year	(9,752)	24,204
Intangible assets subject to amortization, ending balance	254,430	247,559	254,459
Customer relationships
Finite-lived Intangible Assets [Roll Forward]
Intangible assets subject to amortization, beginning balance	234,835	235,704
Intangible assets acquired during the year	47,361	3,175
Amortization during the year	(28,389)	(26,602)
Currency translation during the year	(9,179)	22,558
Intangible assets subject to amortization, ending balance	244,628	234,835	235,704
Patents
Finite-lived Intangible Assets [Roll Forward]
Intangible assets subject to amortization, beginning balance	7,061	13,424
Intangible assets acquired during the year	0	0
Amortization during the year	(2,272)	(7,543)
Currency translation during the year	(294)	1,180
Intangible assets subject to amortization, ending balance	4,495	7,061	13,424
Other
Finite-lived Intangible Assets [Roll Forward]
Intangible assets subject to amortization, beginning balance	5,663	5,331
Intangible assets acquired during the year	7	0
Amortization during the year	(84)	(134)
Currency translation during the year	(279)	466
Intangible assets subject to amortization, ending balance	$ 5,307	$ 5,663	$ 5,331