Industry Segment Information (Schedule of Sales and Operating Income by Operating Segment, Excluding Discontinued Operations) (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jul. 01, 2012	Jun. 30, 2013	Jul. 01, 2012
Segment Reporting [Abstract]
Defined Benefit Plan, Recognized Net (Gain) Loss on Mark-to-Market	$ 0	$ 0	$ (50,000)	$ 1,200,000
Segment Reporting Information [Line Items]
Revenue	543,297,000	521,790,000	1,048,675,000	1,032,680,000
Operating income (loss) from continuing operations	39,664,000	49,787,000	75,565,000	86,169,000
Interest and other expense, net	12,865,000	11,358,000	24,905,000	24,188,000
Income from continuing operations before income taxes	26,799,000	38,429,000	50,660,000	61,981,000
Sales Revenue, Goods, Net	374,025,000	364,243,000	720,644,000	721,436,000
Sales Revenue, Services, Net	169,272,000	157,547,000	328,031,000	311,244,000
Human Health [Member]
Segment Reporting Information [Line Items]
Revenue	299,943,000	287,753,000	581,272,000	568,531,000
Operating income (loss) from continuing operations	30,076,000	30,353,000	55,096,000	48,564,000
Sales Revenue, Goods, Net	235,924,000	226,764,000	454,997,000	446,546,000
Sales Revenue, Services, Net	64,019,000	60,989,000	126,275,000	121,985,000
Environmental Health [Member]
Segment Reporting Information [Line Items]
Revenue	243,354,000	234,037,000	467,403,000	464,149,000
Operating income (loss) from continuing operations	19,298,000	29,344,000	40,026,000	59,473,000
Sales Revenue, Goods, Net	138,101,000	137,479,000	265,647,000	274,890,000
Sales Revenue, Services, Net	105,253,000	96,558,000	201,756,000	189,259,000
Corporate [Member]
Segment Reporting Information [Line Items]
Operating income (loss) from continuing operations	$ (9,710,000)	$ (9,910,000)	$ (19,557,000)	$ (21,868,000)