Revenue from Contracts with Customers (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
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 731,366	$ 721,996	$ 1,410,818	$ 1,382,817
Contract with Customer, Asset, after Allowance for Credit Loss	22,100		22,100		$ 12,400
Americas [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	292,345	274,328	550,978	526,607
Europe [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	207,309	220,718	416,864	426,558
Asia [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	231,712	226,950	442,976	429,652
Product [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	565,927	562,476	1,090,274	1,073,422
Service [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	127,990	123,839	247,932	237,539
Service [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 37,449	35,681	$ 72,612	71,856
Laboratory products and services [Member]
Disaggregation of Revenue [Line Items]
Percentage of Disaggregated Revenue in Relationship to Segments	52.00%		52.00%
Revenue from Contract with Customer, Excluding Assessed Tax	$ 379,659	361,726	$ 739,392	706,885
Industrial products and services [Member]
Disaggregation of Revenue [Line Items]
Percentage of Disaggregated Revenue in Relationship to Segments	41.00%		41.00%
Revenue from Contract with Customer, Excluding Assessed Tax	$ 303,059	305,277	$ 574,379	567,933
Retail products and services [Member]
Disaggregation of Revenue [Line Items]
Percentage of Disaggregated Revenue in Relationship to Segments	7.00%		7.00%
Revenue from Contract with Customer, Excluding Assessed Tax	$ 48,648	54,993	$ 97,047	107,999
US Operations [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	267,889	251,474	502,540	481,219
US Operations [Member] | Product [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	202,608	191,511	376,864	364,012
US Operations [Member] | Service [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	53,054	49,985	102,707	97,605
US Operations [Member] | Service [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	12,227	9,978	22,969	19,602
Swiss Operations [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	31,358	32,154	64,935	64,619
Swiss Operations [Member] | Product [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	24,362	25,163	51,027	50,728
Swiss Operations [Member] | Service [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	5,035	4,919	9,985	9,748
Swiss Operations [Member] | Service [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1,961	2,072	3,923	4,143
Western European Operations [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	163,681	173,772	329,587	339,144
Western European Operations [Member] | Product [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	115,195	124,336	231,751	241,268
Western European Operations [Member] | Service [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	32,553	33,081	65,328	62,966
Western European Operations [Member] | Service [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	15,933	16,355	32,508	34,910
Chinese Operations [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	136,459	133,272	258,181	247,202
Chinese Operations [Member] | Product [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	124,042	119,709	235,457	224,002
Chinese Operations [Member] | Service [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	9,548	10,885	17,252	18,012
Chinese Operations [Member] | Service [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	2,869	2,678	5,472	5,188
Other Operations [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	131,979	131,324	255,575	250,633
Other Operations [Member] | Product [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	99,720	101,757	195,175	193,412
Other Operations [Member] | Service [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	27,800	24,969	52,660	49,208
Other Operations [Member] | Service [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 4,459	$ 4,598	$ 7,740	$ 8,013