Industry Segment and Geographic Area Information Schedule of Depreciation, Amortization and Capital Expenditures (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 28, 2014	Dec. 29, 2013	Dec. 30, 2012
Segment Reporting Information [Line Items]
Depreciation and amortization expense	$ 116,736	$ 126,879	$ 125,126
Human Health [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization expense	89,969	98,582	99,597
Capital expenditures	15,201	20,900	24,518
Environmental Health [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization expense	24,736	25,915	23,001
Capital expenditures	12,149	16,532	14,488
Corporate [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization expense	2,031	2,382	2,528
Capital expenditures	1,722	1,549	3,395
Continuing Operations [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization expense	116,736	126,879	125,126
Capital expenditures	29,072	38,981	42,401
Discontinued Operations [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization expense	339	1,590	1,741
Capital expenditures	$ 213	$ 10	$ 7