Business Combinations and Asset Purchases (Narrative) (Details) (USD $)	12 Months Ended			1 Months Ended
	Dec. 28, 2014	Dec. 29, 2013	Dec. 30, 2012	Nov. 30, 2012	Dec. 28, 2014	Jan. 01, 2012	Dec. 05, 2014	Oct. 21, 2014
Business Acquisition [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value	$ 91,000	$ 4,926,000	$ 3,017,000		$ 91,000	$ 20,298,000
Business Combination, Contingent Consideration Arrangements, Description	Contingent consideration is measured at fair value at the acquisition date, based on the probability that revenue thresholds or product development milestones will be achieved during the earnout period. The earnout periods for each of these acquisitions does not exceed three years from the acquisition date, and the remaining weighted average earnout period at December 28, 2014 was one year.
Business Acquisition, Transaction Costs	3,100,000	100,000	1,200,000
Number of Years in Measurement Period from Acquisition Date to Change Underlying Assumptions	1 year
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High	31,400,000				31,400,000
Perten Instruments Group AB [Member]
Business Acquisition [Line Items]
Business Acquisition, Goodwill, Expected Tax Deductible Amount							0
Fiscal Year 2014 Acquisitions (excluding Perten) [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Cash Paid	17,898,000
Working capital and other adjustments	(151,000)
Business Acquisition, Goodwill, Expected Tax Deductible Amount								0
Business Acquisition, Cost of Acquired Entity, Cash Paid Including Working Capital And Other Adjustments	18,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt								4,287,000
Fiscal Year 2013 Acquisitions [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Cash Paid	400,000	11,400,000
Contingent consideration		1,100,000
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High		2,200,000
Human Health [Member] | Haoyuan Biotech Co. [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Cash Paid				38,000,000
Working capital and other adjustments				2,729,000
Contingent consideration				1,900,000
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High				30,000,000
Human Health [Member] | Core Technology [Member] | Haoyuan Biotech Co. [Member]
Business Acquisition [Line Items]
Weighted average amortization period (in years)				8 years
Human Health [Member] | Trade Names [Member] | Haoyuan Biotech Co. [Member]
Business Acquisition [Line Items]
Weighted average amortization period (in years)				8 years
Environmental Health [Member] | Perten Instruments Group AB [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Cash Paid					269,937,000
Working capital and other adjustments					0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt							$ 7,600,000
Environmental Health [Member] | Minimum [Member] | Perten Instruments Group AB [Member]
Business Acquisition [Line Items]
Weighted average amortization period (in years)					5 years
Environmental Health [Member] | Maximum [Member] | Perten Instruments Group AB [Member]
Business Acquisition [Line Items]
Weighted average amortization period (in years)					10 years