Goodwill and Other Intangible Assets - Net Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Intangible Assets, Net:
Cost	$ 900,937	$ 912,031
Acquisitions	12,789	2,092
Currency translation	66,584	(13,186)
Accumulated amortization	755,971	674,790
Net Value	224,339	226,147	$ 254,430
Customer relationships
Intangible Assets, Net:
Cost	645,206	651,014
Acquisitions	12,789	2,092
Currency translation	41,800	(7,900)
Accumulated amortization	481,256	426,765
Net Value	218,539	218,441	244,628
Patents
Intangible Assets, Net:
Cost	249,100	254,483
Acquisitions	0	0
Currency translation	24,470	(5,383)
Accumulated amortization	273,426	246,872
Net Value	144	2,228	$ 4,495
Other
Intangible Assets, Net:
Cost	6,631	6,534
Acquisitions	0	0
Currency translation	314	97
Accumulated amortization	1,289	1,153
Net Value	$ 5,656	$ 5,478