Goodwill and Other Intangible Assets (Net intangible assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Intangible Assets, Net:
Cost	$ 899,057	$ 810,332
Acquisitions	47,368	3,175
Currency translation	(34,394)	85,550
Accumulated amortization	657,601	651,498
Net Value	254,430	247,559	$ 254,459
Customer relationships
Intangible Assets, Net:
Cost	625,263	569,980
Acquisitions	47,361	3,175
Currency translation	(21,610)	52,108
Accumulated amortization	406,386	390,428
Net Value	244,628	234,835	235,704
Patents
Intangible Assets, Net:
Cost	266,969	234,022
Acquisitions	0	0
Currency translation	(12,486)	32,947
Accumulated amortization	249,988	259,908
Net Value	4,495	7,061	$ 13,424
Other
Intangible Assets, Net:
Cost	6,825	6,330
Acquisitions	7	0
Currency translation	(298)	495
Accumulated amortization	1,227	1,162
Net Value	$ 5,307	$ 5,663