Segment Reporting (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Operations of the Company's operating segments
Net Sales to External Customers	$ 731,366	$ 721,996	$ 1,410,818	$ 1,382,817
Revenue Transactions With Other Operating Segments	0	0	0	0
Net Sales	731,366	721,996	1,410,818	1,382,817
Segment Profit	177,741	169,286	325,582	308,832
Goodwill	534,557	536,407	534,557	536,407	$ 534,780
US Operations [Member]
Operations of the Company's operating segments
Net Sales to External Customers	267,889	251,474	502,540	481,219
Revenue Transactions With Other Operating Segments	26,571	23,487	52,716	47,153
Net Sales	294,460	274,961	555,256	528,372
Segment profit	53,986	42,006	91,971	76,251
Goodwill	410,021	409,470	410,021	409,470
Swiss Operations [Member]
Operations of the Company's operating segments
Net Sales to External Customers	31,358	32,154	64,935	64,619
Revenue Transactions With Other Operating Segments	151,931	148,959	305,662	292,541
Net Sales	183,289	181,113	370,597	357,160
Segment profit	48,613	47,737	102,135	93,712
Goodwill	22,157	21,787	22,157	21,787
Western European Operations [Member]
Operations of the Company's operating segments
Net Sales to External Customers	163,681	173,772	329,587	339,144
Revenue Transactions With Other Operating Segments	39,212	45,141	83,257	86,153
Net Sales	202,893	218,913	412,844	425,297
Segment profit	22,229	27,333	47,954	45,615
Goodwill	86,749	89,412	86,749	89,412
Chinese Operations [Member]
Operations of the Company's operating segments
Net Sales to External Customers	136,459	133,272	258,181	247,202
Revenue Transactions With Other Operating Segments	52,568	58,588	109,425	118,995
Net Sales	189,027	191,860	367,606	366,197
Segment profit	65,489	65,884	124,973	125,437
Goodwill	643	678	643	678
Other Operations [Member]
Operations of the Company's operating segments
Net Sales to External Customers	131,979	131,324	255,575	250,633
Revenue Transactions With Other Operating Segments	1,334	1,463	2,595	3,103
Net Sales	133,313	132,787	258,170	253,736
Segment profit	14,300	17,642	27,487	31,523
Goodwill	14,987	15,060	14,987	15,060
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	(271,616)	(277,638)	(553,655)	(547,945)
Net Sales	(271,616)	(277,638)	(553,655)	(547,945)
Segment profit	(26,876)	(31,316)	(68,938)	(63,706)
Goodwill	$ 0	$ 0	$ 0	$ 0