Goodwill and Other Intangible Assets (Net intangible assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Intangible Assets, Net:
Cost	$ 912,031	$ 899,057
Acquisitions	2,092	47,368
Currency translation	(13,186)	(34,394)
Accumulated amortization	674,790	657,601
Net Value	226,147	254,430	$ 247,559
Customer relationships
Intangible Assets, Net:
Cost	651,014	625,263
Acquisitions	2,092	47,361
Currency translation	(7,900)	(21,610)
Accumulated amortization	426,765	406,386
Net Value	218,441	244,628	234,835
Patents
Intangible Assets, Net:
Cost	254,483	266,969
Acquisitions	0	0
Currency translation	(5,383)	(12,486)
Accumulated amortization	246,872	249,988
Net Value	2,228	4,495	$ 7,061
Other
Intangible Assets, Net:
Cost	6,534	6,825
Acquisitions	0	7
Currency translation	97	(298)
Accumulated amortization	1,153	1,227
Net Value	$ 5,478	$ 5,307