Business Combinations and Asset Purchases (Narrative) (Details)	3 Months Ended							6 Months Ended	12 Months Ended
	Dec. 31, 2017 USD ($) employees	Oct. 01, 2017 USD ($)	Jul. 02, 2017 USD ($)	Apr. 02, 2017 USD ($)	Jan. 01, 2017 USD ($)	Oct. 02, 2016 USD ($)	Apr. 03, 2016 USD ($)	Jul. 03, 2016 USD ($)	Dec. 31, 2017 USD ($) employees $ / shares	Jan. 01, 2017 USD ($) $ / shares	Jan. 03, 2016 USD ($)
Business Acquisition [Line Items]
Revenue	$ 641,630,000	$ 554,275,000	$ 546,962,000	$ 514,115,000	$ 566,770,000	$ 514,489,000	$ 498,016,000	$ 536,242,000	$ 2,256,982,000	$ 2,115,517,000
Business Combination, Contingent Consideration, Liability, Current	(52,200,000)				(15,400,000)				(52,200,000)	(15,400,000)
Business Combination, Contingent Consideration, Liability, Noncurrent	13,100,000				47,800,000				13,100,000	47,800,000
Business Combination, Contingent Consideration, Liability, Total	65,328,000				63,200,000				$ 65,328,000	63,200,000
Business Combination, Contingent Consideration Arrangements, Maximum Period									1 year 9 months
Business Combination, Contingent Consideration Arrangements, Description									Contingent consideration is measured at fair value at the acquisition date using projected milestone dates, discount rates, probabilities of success and projected revenues (for revenue-based considerations). The expected maximum earnout period for an acquisition with open contingency period do not exceed 1.75 years from the acquisition date, and the remaining weighted average expected earnout period at December 31, 2017 was 11 months.
Goodwill	3,002,198,000				2,247,966,000				$ 3,002,198,000	2,247,966,000	$ 2,236,863,000
Number of Years in Measurement Period from Acquisition Date to Change Underlying Assumptions									1 year
Business Combination, Contingent Consideration Arrangements, Weighted Average Period									11 years
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High	83,000,000								$ 83,000,000
Business Acquisition and Divestiture, Transaction Costs									10,800,000	1,200,000	700,000
Tulip Diagnostics Private Limited [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	$ 1,713,000								$ 1,713,000
Weighted average amortization period (in years)									11 years 9 months
Business Acquisition, Cost of Acquired Entity, Cash Paid Including Working Capital And Other Adjustments									$ 127,280,000
EUROIMMUM [Member]
Business Acquisition [Line Items]
Business Acquisition, Percentage of Voting Interests Acquired	99.98%								99.98%
Business Acquisition, Pro Forma Revenue									$ 2,562,580,000	2,379,176,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets	$ 121,174,000								121,174,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	(87,631,000)								(87,631,000)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	129,964,000								129,964,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets	49,944,000								49,944,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	1,388,762,000								1,388,762,000
Intangible Assets, Gross (Excluding Goodwill)	897,400,000								897,400,000
Business Acquisition, Cost of Acquired Entity, Cash Paid									1,413,780,000
Business Combination, Consideration Transferred, Liabilities Incurred									$ 0
Weighted average amortization period (in years)									16 years 1 month
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual									$ 13,500,000
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual									(1,000,000)
Business Acquisition, Transaction Costs	$ 9,800,000								$ 9,800,000
Entity Number of Employees | employees	2,400								2,400
Goodwill	$ 614,759,000								$ 614,759,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities, Total	(275,491,000)								(275,491,000)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt	(61,357,000)								(61,357,000)
Cash Acquired									(25,018,000)
Business Combination, Consideration Transferred									1,388,762,000.000
Business Acquisition, Pro Forma Income (Loss) from Continuing Operations, Net of Tax									$ 143,459,000	$ 156,210,000
Business Acquisition, Pro Forma Earnings Per Share, Basic | $ / shares									$ 1.31	$ 1.43
Business Acquisition, Pro Forma Earnings Per Share, Diluted | $ / shares									$ 1.29	$ 1.42
Fiscal Year 2017 Acquisitions [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Cash Paid Including Working Capital And Other Adjustments									$ 142,134,000
Fiscal Year 2017 Other Acquisitions [Member]
Business Acquisition [Line Items]
Aggregate Revenue from Immaterial Acquisitions									38,500,000
Operating Income (Loss) From Immaterial Acquisitions									0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets	16,268,000								16,268,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	(8,759,000)								(8,759,000)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	11,356,000								11,356,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets	1,691,000								1,691,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	139,695,000								139,695,000
Business Acquisition, Cost of Acquired Entity, Cash Paid									140,861,000
Business Combination, Consideration Transferred, Liabilities Incurred									1,273,000
Business Acquisition, Cost of Acquired Entity, Cash Paid Including Working Capital And Other Adjustments									14,844,000
Goodwill	75,453,000								75,453,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities, Total	(15,414,000)								(15,414,000)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt	0								0
Cash Acquired									(2,439,000)
Business Combination, Consideration Transferred									139,695,000.000
2016 Acquisitions (excluding Bioo) [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Cash Paid Including Working Capital And Other Adjustments										$ 8,800,000
Fiscal Year 2016 Acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets					7,153,000					7,153,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities					(1,985,000)					(1,985,000)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment					7,542,000					7,542,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net					70,084,000					70,084,000
Intangible Assets, Gross (Excluding Goodwill)					22,100,000					22,100,000
Business Acquisition, Cost of Acquired Entity, Cash Paid										$ 72,497,000
Weighted average amortization period (in years)										9 years 5 months
Business Acquisition, Cost of Acquired Entity, Cash Paid Including Working Capital And Other Adjustments										$ 72,300,000
Goodwill					43,072,000					43,072,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities, Total					(7,768,000)					(7,768,000)
Working capital and other adjustments										(261,000)
Cash Acquired										(2,152,000)
Business Combination, Consideration Transferred										70,084,000
Bioo Scientific Corporation [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets	140,000								140,000
Business Acquisition, Cost of Acquired Entity, Cash Paid Including Working Capital And Other Adjustments										63,500,000
Goodwill	(2,576,000)								(2,576,000)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities, Total	(516,000)								(516,000)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill	2,200,000								2,200,000
Fiscal Year 2015 Acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets											2,551,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities											(2,850,000)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment											998,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net											130,131,000
Business Acquisition, Cost of Acquired Entity, Cash Paid											75,285,000
Business Acquisition, Goodwill, Expected Tax Deductible Amount											9,200,000
Business Acquisition, Cost of Acquired Entity, Liabilities Incurred, Contingent Consideration at Fair Value											(56,878,000)
Business Acquisition, Cost of Acquired Entity, Cash Paid Including Working Capital And Other Adjustments											77,117,000
Goodwill											53,112,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities, Total											(18,528,000)
Working capital and other adjustments											1,832,000
Cash Acquired											(3,864,000)
Business Combination, Consideration Transferred											130,131,000
Vanadis Diagnostics AB [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Liabilities Incurred, Contingent Consideration at Fair Value									(65,300,000)		56,878,000
Business Acquisition, Cost of Acquired Entity, Cash Paid Including Working Capital And Other Adjustments											35,141,000
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High											93,000,000
2015 Acquisitions (excluding Vanadis) [Domain]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Cash Paid Including Working Capital And Other Adjustments											41,976,000
Core Technology [Member] | EUROIMMUM [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	160,000,000								160,000,000
Core Technology [Member] | Fiscal Year 2017 Other Acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	12,400,000								12,400,000
Core Technology [Member] | Fiscal Year 2016 Acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles					6,600,000					$ 6,600,000
Core Technology [Member] | Fiscal Year 2015 Acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles											15,759,000
Weighted average amortization period (in years)										9 years
Trade Names [Member] | EUROIMMUM [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	36,000,000								36,000,000
Trade Names [Member] | Fiscal Year 2017 Other Acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	3,000,000								3,000,000
Trade Names [Member] | Fiscal Year 2016 Acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles					570,000					$ 570,000
Trade Names [Member] | Fiscal Year 2015 Acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles											200,000
Licenses [Member] | Fiscal Year 2015 Acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles											116,000
Customer Relationships [Member] | EUROIMMUM [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	700,000,000								700,000,000
Customer Relationships [Member] | Fiscal Year 2017 Other Acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	43,700,000								43,700,000
Customer Relationships [Member] | Fiscal Year 2016 Acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles					14,900,000					14,900,000
Customer Relationships [Member] | Fiscal Year 2015 Acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles											3,073,000
In Process Research and Development [Member] | EUROIMMUM [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	1,400,000								1,400,000
In Process Research and Development [Member] | Fiscal Year 2017 Other Acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	0								0
In Process Research and Development [Member] | Fiscal Year 2015 Acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles											75,700,000
Diagnostics [Member]
Business Acquisition [Line Items]
Goodwill	1,657,963,000				944,030,000				1,657,963,000	944,030,000	940,139,000
Discovery & Analytical Solutions [Member]
Business Acquisition [Line Items]
Goodwill	1,344,235,000				$ 1,303,936,000				1,344,235,000	$ 1,303,936,000	$ 1,296,724,000
Euro Member Countries, Euro | EUROIMMUM [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Cash Paid Including Working Capital And Other Adjustments									1,200,000,000
United States of America, Dollars | Tulip Diagnostics Private Limited [Member]
Business Acquisition [Line Items]
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High	25,200,000								25,200,000
United States of America, Dollars | EUROIMMUM [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Cash Paid Including Working Capital And Other Adjustments									1,413,780,000
United States of America, Dollars | EUROIMMUM [Member] | Term Loan Credit Facility, 12 Months Maturity [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Cash Paid Including Working Capital And Other Adjustments									200,000,000
United States of America, Dollars | EUROIMMUM [Member] | Line of Credit, Maturing August 11, 2021 [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Cash Paid Including Working Capital And Other Adjustments									710,000,000
United States of America, Dollars | EUROIMMUM [Member] | Cash and Cash Equivalents [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Cash Paid Including Working Capital And Other Adjustments									503,780,000
India, Rupees | Tulip Diagnostics Private Limited [Member]
Business Acquisition [Line Items]
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High	$ 1,600,000,000								$ 1,600,000,000