Industry Segment Information (Schedule of Sales and Operating Income by Operating Segment, Excluding Discontinued Operations) (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended	9 Months Ended
	Oct. 04, 2015	Sep. 28, 2014		Jun. 29, 2014	Oct. 04, 2015	Sep. 28, 2014
Segment Reporting Information [Line Items]
Product revenue	$ 378,325	$ 365,933			$ 1,126,356	$ 1,113,027
Service revenue	185,111	176,116			527,887	515,802
Total revenue	563,436	542,049			1,654,243	1,628,829
Operating income (loss) from continuing operations	75,898	58,776			201,410	180,175
Interest and other expense, net	11,944	10,966			32,208	31,219
Income from continuing operations before income taxes	63,954	47,810			169,202	148,956
Human Health [Member]
Segment Reporting Information [Line Items]
Product revenue	238,553	237,312			712,207	721,449
Service revenue	105,083	99,637			298,970	288,076
Total revenue	343,636	336,949			1,011,177	1,009,525
Operating income (loss) from continuing operations	63,147	48,089			179,560	149,979
Environmental Health [Member]
Segment Reporting Information [Line Items]
Product revenue	139,772	128,621			414,149	391,578
Service revenue	80,028	76,479			228,917	227,726
Total revenue	219,800	205,100			643,066	619,304
Operating income (loss) from continuing operations	22,838	18,540			53,606	65,725
Corporate [Member]
Segment Reporting Information [Line Items]
Operating income (loss) from continuing operations	$ (10,087)	$ (7,853)	[1]		$ (31,756)	$ (35,529)	[1]
Enzo Biochem, Inc. Complaint [Member]
Segment Reporting Information [Line Items]
Litigation Settlement, Expense				$ 3,400

[1] In 2002, Enzo Biochem, Inc. and Enzo Life Sciences, Inc. (collectively, “Enzo”) filed a complaint that alleged that the Company separately and together with other defendants breached distributorship and settlement agreements with Enzo, infringed Enzo's patents, engaged in unfair competition and fraud, and committed torts against Enzo by, among other things, engaging in commercial development and exploitation of Enzo's patented products and technology. The Company entered into a settlement agreement with Enzo dated June 20, 2014 and during fiscal year 2014 paid $7.0 million into a designated escrow account to resolve this matter, of which $3.7 million had been accrued in previous years and $3.3 million was recorded in the second quarter of fiscal year 2014. In addition, the Company incurred $3.4 million of expenses in preparation for the trial during the six months ended June 29, 2014.