Segment Reporting Detail 2 (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
Segment Sales Information
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
Laboratory Product and Service Sales [Member]
Segment Sales Information
Revenues										1,358,493	1,225,000
Industrial Product and Service Sales [Member]
Segment Sales Information
Revenues										1,158,335	1,067,858
Retail Product and Service Sales [Member]
Segment Sales Information
Revenues										$ 208,225	$ 215,399