Segment Reporting Segment Details - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues	$ 937,985	$ 807,357	$ 690,673	$ 649,162	$ 843,968	$ 753,866	$ 731,366	$ 679,452	$ 3,085,177	$ 3,008,652	$ 2,935,586
Revenue Transactions With Other Operating Segments									0	0	0
Net Sales									3,085,177	3,008,652	2,935,586
Total Segment Profit									840,708	778,078	730,505
Depreciation									42,044	38,991	37,167
Assets	2,814,549				2,789,321				2,814,549	2,789,321	2,618,847
Purchase of property, plant and equipment									(92,494)	(97,341)	(142,726)
Goodwill	550,270				535,979				550,270	535,979	534,780
U.S. Operations Segment
Revenues									1,072,319	1,057,115	1,007,798
Revenue Transactions With Other Operating Segments									121,850	114,794	104,458
Net Sales									1,194,169	1,171,909	1,112,256
Segment Profit									244,940	210,133	161,615
Depreciation									11,347	10,684	10,425
Assets	2,560,652				2,363,725				2,560,652	2,363,725	2,113,268
Purchase of property, plant and equipment									(18,258)	(15,607)	(27,896)
Goodwill	415,869				410,022				415,869	410,022	410,021
Swiss Operations Segment
Revenues									143,923	139,499	134,064
Revenue Transactions With Other Operating Segments									679,837	657,678	628,529
Net Sales									823,760	797,177	762,593
Segment Profit									245,465	233,292	202,027
Depreciation									6,257	6,069	5,835
Assets	2,028,879				1,648,065				2,028,879	1,648,065	1,471,625
Purchase of property, plant and equipment									(5,495)	(5,820)	(1,123)
Goodwill	24,525				22,369				24,525	22,369	21,994
Western European Operations Segment
Revenues									716,715	700,741	718,788
Revenue Transactions With Other Operating Segments									173,176	175,759	176,995
Net Sales									889,891	876,500	895,783
Segment Profit									147,562	123,845	122,574
Depreciation									4,769	4,450	4,173
Assets	1,294,579				1,150,214				1,294,579	1,150,214	983,809
Purchase of property, plant and equipment									(13,678)	(11,267)	(16,879)
Goodwill	93,514				87,980				93,514	87,980	87,242
Chinese Operations Segment
Revenues									578,610	544,716	525,109
Revenue Transactions With Other Operating Segments									213,735	224,517	242,452
Net Sales									792,345	769,233	767,561
Segment Profit									270,497	266,522	270,668
Depreciation									8,506	8,045	7,869
Assets	985,977				694,903				985,977	694,903	1,237,248
Purchase of property, plant and equipment									(9,755)	(10,252)	(13,248)
Goodwill	686				633				686	633	644
Other Operations Segment
Revenues									573,610	566,581	549,827
Revenue Transactions With Other Operating Segments									4,600	5,890	6,543
Net Sales									578,210	572,471	556,370
Segment Profit									77,910	71,483	78,317
Depreciation									3,737	3,395	3,774
Assets	340,786				358,281				340,786	358,281	319,070
Purchase of property, plant and equipment									(5,974)	(4,936)	(8,342)
Goodwill	15,676				14,975				15,676	14,975	14,879
Eliminations and Corporate Segment
Revenues									0	0	0
Revenue Transactions With Other Operating Segments									(1,193,198)	(1,178,638)	(1,158,977)
Net Sales									(1,193,198)	(1,178,638)	(1,158,977)
Segment Profit									(145,666)	(127,197)	(104,696)
Depreciation									7,428	6,348	5,091
Assets	(4,396,324)				(3,425,867)				(4,396,324)	(3,425,867)	(3,506,173)
Purchase of property, plant and equipment									(39,334)	(49,459)	(75,238)
Goodwill	$ 0				$ 0				$ 0	$ 0	$ 0