Segment Reporting (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues	$ 817,923	$ 734,846	$ 721,996	$ 660,821	$ 778,031	$ 698,799	$ 653,656	$ 594,567	$ 2,935,586	$ 2,725,053	$ 2,508,257
Revenue Transactions With Other Operating Segments									0	0	0
Net Sales									2,935,586	2,725,053	2,508,257
Total Segment Profit									730,505	652,582	573,178
Depreciation									37,167	33,458	32,743
Assets	2,618,847				2,549,805				2,618,847	2,549,805	2,166,777
Purchase of property, plant and equipment									(142,726)	(127,426)	(123,957)
Goodwill	534,780				539,838				534,780	539,838	476,378
U.S. Operations Segment
Revenues									1,007,798	944,825	867,962
Revenue Transactions With Other Operating Segments									104,458	99,117	90,580
Net Sales									1,112,256	1,043,942	958,542
Segment Profit									161,615	177,705	161,539
Depreciation									10,425	7,659	6,094
Assets	2,113,268				1,937,688				2,113,268	1,937,688	1,747,338
Purchase of property, plant and equipment									(27,896)	(38,969)	(52,255)
Goodwill	410,021				409,520				410,021	409,520	357,785
Swiss Operations Segment
Revenues									134,064	133,925	130,674
Revenue Transactions With Other Operating Segments									628,529	563,083	524,983
Net Sales									762,593	697,008	655,657
Segment Profit									202,027	174,447	163,663
Depreciation									5,835	5,551	6,199
Assets	1,471,625				1,374,150				1,471,625	1,374,150	1,212,637
Purchase of property, plant and equipment									(1,123)	(19,589)	(7,260)
Goodwill	21,994				22,171				21,994	22,171	21,239
Western European Operations Segment
Revenues									718,788	673,776	640,558
Revenue Transactions With Other Operating Segments									176,995	170,820	176,501
Net Sales									895,783	844,596	817,059
Segment Profit									122,574	123,841	129,001
Depreciation									4,173	4,052	4,048
Assets	983,809				1,805,294				983,809	1,805,294	1,120,751
Purchase of property, plant and equipment									(16,879)	(7,094)	(6,857)
Goodwill	87,242				91,927				87,242	91,927	82,500
Chinese Operations Segment
Revenues									525,109	452,617	386,541
Revenue Transactions With Other Operating Segments									242,452	232,882	219,766
Net Sales									767,561	685,499	606,307
Segment Profit									270,668	231,860	187,924
Depreciation									7,869	7,168	6,879
Assets	1,237,248				1,068,811				1,237,248	1,068,811	702,571
Purchase of property, plant and equipment									(13,248)	(13,246)	(16,288)
Goodwill	644				690				644	690	636
Other Operations Segment
Revenues									549,827	519,910	482,522
Revenue Transactions With Other Operating Segments									6,543	7,934	7,709
Net Sales									556,370	527,844	490,231
Segment Profit									78,317	72,681	64,146
Depreciation									3,774	3,474	3,461
Assets	319,070				310,667				319,070	310,667	277,476
Purchase of property, plant and equipment									(8,342)	(4,131)	(4,540)
Goodwill	14,879				15,530				14,879	15,530	14,218
Eliminations and Corporate Segment
Revenues									0	0	0
Revenue Transactions With Other Operating Segments									(1,158,977)	(1,073,836)	(1,019,539)
Net Sales									(1,158,977)	(1,073,836)	(1,019,539)
Segment Profit									(104,696)	(127,952)	(133,095)
Depreciation									5,091	5,554	6,062
Assets	(3,506,173)				(3,946,805)				(3,506,173)	(3,946,805)	(2,893,996)
Purchase of property, plant and equipment									(75,238)	(44,397)	(36,757)
Goodwill	$ 0				$ 0				$ 0	$ 0	$ 0