Segment Reporting (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Operations of the Company's operating segments
Net Sales to External Customers	$ 807,357	$ 753,866	$ 2,147,192	$ 2,164,684
Revenue Transactions With Other Operating Segments	0	0	0	0
Net Sales	807,357	753,866	2,147,192	2,164,684
Segment Profit	229,978	196,215	547,899	521,797
Goodwill	541,722		541,722		$ 535,979	$ 531,224
US Operations [Member]
Operations of the Company's operating segments
Net Sales to External Customers	278,948	269,038	769,696	771,578
Revenue Transactions With Other Operating Segments	30,857	28,075	84,761	80,791
Net Sales	309,805	297,113	854,457	852,369
Segment profit	65,493	54,628	163,012	146,599
Goodwill	414,370		414,370			410,021
Swiss Operations [Member]
Operations of the Company's operating segments
Net Sales to External Customers	38,848	33,415	99,693	98,350
Revenue Transactions With Other Operating Segments	167,335	160,736	462,671	466,398
Net Sales	206,183	194,151	562,364	564,748
Segment profit	61,902	54,226	164,060	156,361
Goodwill	23,353		23,353			21,803
Western European Operations [Member]
Operations of the Company's operating segments
Net Sales to External Customers	177,630	168,652	480,006	498,240
Revenue Transactions With Other Operating Segments	42,130	42,794	123,543	126,050
Net Sales	219,760	211,446	603,549	624,290
Segment profit	36,954	29,888	91,406	77,842
Goodwill	88,292		88,292			83,971
Chinese Operations [Member]
Operations of the Company's operating segments
Net Sales to External Customers	165,231	142,292	406,738	400,473
Revenue Transactions With Other Operating Segments	54,314	60,710	148,794	170,135
Net Sales	219,545	203,002	555,532	570,608
Segment profit	81,055	72,745	190,560	197,718
Goodwill	651		651			615
Other Operations [Member]
Operations of the Company's operating segments
Net Sales to External Customers	146,700	140,469	391,059	396,043
Revenue Transactions With Other Operating Segments	1,509	1,513	3,281	4,108
Net Sales	148,209	141,982	394,340	400,151
Segment profit	23,554	17,938	47,702	45,425
Goodwill	15,056		15,056			14,814
Intersegment Elimination [Member]
Operations of the Company's operating segments
Net Sales to External Customers	0	0	0	0
Revenue Transactions With Other Operating Segments	(296,145)	(293,828)	(823,050)	(847,482)
Net Sales	(296,145)	(293,828)	(823,050)	(847,482)
Segment profit	(38,980)	$ (33,210)	(108,841)	$ (102,148)
Goodwill	$ 0		$ 0			$ 0