Business Combinations and Asset Purchases (Narrative) (Details)	3 Months Ended								12 Months Ended
	Jan. 03, 2021 USD ($) employees	Oct. 04, 2020 USD ($)	Jul. 05, 2020 USD ($)	Apr. 05, 2020 USD ($)	Dec. 29, 2019 USD ($)	Sep. 29, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Jan. 03, 2021 USD ($) employees	Dec. 29, 2019 USD ($)	Dec. 30, 2018 USD ($)	Jan. 01, 2017 USD ($)
Business Acquisition [Line Items]
Revenue	$ 1,354,606,000	$ 964,025,000	$ 811,718,000	$ 652,396,000	$ 805,496,000	$ 706,923,000	$ 722,517,000	$ 648,737,000	$ 3,782,745,000	$ 2,883,673,000
Business Combination, Contingent Consideration, Liability, Current	(2,900,000)				(20,800,000)				(2,900,000)	(20,800,000)
Business Combination, Contingent Consideration, Liability, Noncurrent	100,000				14,700,000				100,000	14,700,000
Business Combination, Contingent Consideration, Liability, Total	(3,000,000.0)				(35,500,000)				$ (3,000,000.0)	(35,500,000)
Business Combination, Contingent Consideration Arrangements, Maximum Period									2 years 10 months 24 days
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 2.9 years from January 3, 2021, and the remaining weighted average expected earnout period at January 3, 2021 was 1.9 years.
Goodwill	3,447,114,000				3,111,227,000				$ 3,447,114,000	3,111,227,000	$ 2,952,608,000
Number of Years in Measurement Period from Acquisition Date to Change Underlying Assumptions									1 year
Business Combination, Contingent Consideration Arrangements, Weighted Average Period									1 year 10 months 24 days
Business Combination, Acquisition Related Costs									$ 9,300,000	6,600,000
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High	7,300,000								7,300,000
Foreign Currency Transaction Gain (Loss), before Tax									2,700,000	(6,500,000)	9,400,000
Interest Expense									49,712,000	63,627,000	66,976,000
Fiscal Year 2020 Other Acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets	5,770,000								5,770,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	(29,000)								(29,000)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	2,673,000								2,673,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets	371,000								371,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	38,030,000								38,030,000
Business Acquisition, Cost of Acquired Entity, Cash Paid									38,243,000
Business Combination, Consideration Transferred, Liabilities Incurred									1,263,000
Goodwill	16,224,000								16,224,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities, Total	(1,132,000)								(1,132,000)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Deferred Revenue	0								0
Working capital and other adjustments									(176,000)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt	(3,180,000)								(3,180,000)
Cash Acquired									(1,300,000)
Business Combination, Consideration Transferred									38,030,000
Horizon Discovery Group plc [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets	29,762,000								29,762,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	0								0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	17,729,000								17,729,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets	17,743,000								17,743,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	$ 373,862,000								373,862,000
Business Acquisition, Cost of Acquired Entity, Cash Paid									399,005,000
Business Combination, Consideration Transferred, Liabilities Incurred									$ 396,000
Entity Number of Employees | employees	400								400
Goodwill	$ 200,745,000								$ 200,745,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities, Total	(22,480,000)								(22,480,000)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Deferred Revenue	2,031,000								2,031,000
Working capital and other adjustments									0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt	(39,906,000)								(39,906,000)
Cash Acquired									(25,539,000)
Business Combination, Consideration Transferred									373,862,000
Fiscal Year 2020 Acquisitions [Member]
Business Acquisition [Line Items]
Operating Income (Loss) From Immaterial Acquisitions									$ 0
Weighted average amortization period (in years)									11 years
Interest Expense									$ 500,000
Fiscal Year 2019 Acquisitions [Member]
Business Acquisition [Line Items]
Operating Income (Loss) From Immaterial Acquisitions										$ 0
Weighted average amortization period (in years)										11 years
Business Combination, Increase (Decrease) in Liabilities Assumed									(400,000)
Business Combination, Increase (Decrease) in Deferred Tax Liabilities									400,000
Goodwill, Purchase Accounting Adjustments									(1,800,000)
Business Combination, Increase (Decrease) in Intangible Assets									1,900,000
Fiscal Year 2019 Other Acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets	4,125,000								4,125,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities					(2,698,000)					$ (2,698,000)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment					727,000					727,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets		502,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net					45,282,000					45,282,000
Business Acquisition, Cost of Acquired Entity, Cash Paid										45,042,000
Business Combination, Consideration Transferred, Liabilities Incurred										638,000
Business Acquisition, Cost of Acquired Entity, Liabilities Incurred, Contingent Consideration at Fair Value										(634,000)
Goodwill					17,079,000					17,079,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities, Total	(6,603,000)								(6,603,000)
Working capital and other adjustments										302,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt	(3,527,000)								(3,527,000)
Cash Acquired										(1,334,000)
Business Combination, Consideration Transferred										45,282,000
Shandong Meizheng [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets	15,077,000								15,077,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities					(706,000)					(706,000)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment					6,278,000					6,278,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets		$ 24,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net					164,399,000					164,399,000
Business Acquisition, Cost of Acquired Entity, Cash Paid										145,000,000
Business Combination, Consideration Transferred, Liabilities Incurred										6,446,000
Business Acquisition, Cost of Acquired Entity, Liabilities Incurred, Contingent Consideration at Fair Value										(12,100,000)
Goodwill	78,612,000								78,612,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities, Total	(21,548,000)								(21,548,000)
Working capital and other adjustments										2,961,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt	(10,638,000)								(10,638,000)
Cash Acquired										(2,108,000)
Business Combination, Consideration Transferred										164,399,000
Compensation Expense, Excluding Cost of Good and Service Sold									4,700,000
Cisbio Bioassays SAS [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets					43,554,000					43,554,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities					0					0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment					4,835,000					4,835,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets					100,000					100,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net					207,391,000					207,391,000
Business Acquisition, Cost of Acquired Entity, Cash Paid										219,795,000
Business Combination, Consideration Transferred, Liabilities Incurred										0
Business Acquisition, Cost of Acquired Entity, Liabilities Incurred, Contingent Consideration at Fair Value										0
Goodwill			73,417,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities, Total			$ (34,962,000)
Working capital and other adjustments										138,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt					(12,553,000)					(12,553,000)
Cash Acquired										(12,542,000)
Business Combination, Consideration Transferred										207,391,000
Foreign Currency Transaction Gain (Loss), before Tax										2,600,000
Fiscal Year 2018 Acquisitions [Member]
Business Acquisition [Line Items]
Operating Income (Loss) From Immaterial Acquisitions											0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets					4,905,000					4,905,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities											(461,000)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment					1,166,000					1,166,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets					776,000					776,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net											104,633,000
Business Acquisition, Cost of Acquired Entity, Cash Paid											95,950,000
Business Combination, Consideration Transferred, Liabilities Incurred											$ 3,354,000
Weighted average amortization period (in years)											11 years 2 months 12 days
Business Acquisition, Cost of Acquired Entity, Liabilities Incurred, Contingent Consideration at Fair Value											$ (6,200,000)
Goodwill											65,886,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities, Total											(9,049,000)
Working capital and other adjustments											261,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt											(3,881,000)
Cash Acquired											(1,132,000)
Business Combination, Consideration Transferred											104,633,000
Tulip Diagnostics Private Limited [Member]
Business Acquisition [Line Items]
Compensation Expense, Excluding Cost of Good and Service Sold										500,000
Vanadis Diagnostics AB [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Liabilities Incurred, Contingent Consideration at Fair Value												$ 56,900,000
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High												$ 93,000,000.0
Core Technology [Member] | Fiscal Year 2020 Other Acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	5,730,000								5,730,000
Core Technology [Member] | Horizon Discovery Group plc [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	60,000,000								60,000,000
Core Technology [Member] | Fiscal Year 2019 Other Acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles					27,667,000					27,667,000
Core Technology [Member] | Shandong Meizheng [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles				36,600,000
Core Technology [Member] | Cisbio Bioassays SAS [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles				89,000,000
Core Technology [Member] | Fiscal Year 2018 Acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles											31,956,000
Trade Names [Member] | Fiscal Year 2020 Other Acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	680,000								680,000
Trade Names [Member] | Horizon Discovery Group plc [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	4,900,000								4,900,000
Trade Names [Member] | Fiscal Year 2019 Other Acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles					1,310,000					1,310,000
Trade Names [Member] | Shandong Meizheng [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles					4,900,000					4,900,000
Trade Names [Member] | Cisbio Bioassays SAS [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles					5,000,000					5,000,000
Trade Names [Member] | Fiscal Year 2018 Acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles											1,070,000
Customer Relationships [Member] | Fiscal Year 2020 Other Acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	10,923,000								10,923,000
Customer Relationships [Member] | Horizon Discovery Group plc [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	96,600,000								96,600,000
Customer Relationships [Member] | Fiscal Year 2019 Other Acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles					6,700,000					6,700,000
Customer Relationships [Member] | Shandong Meizheng [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles				$ 55,800,000
Customer Relationships [Member] | Cisbio Bioassays SAS [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles					39,000,000					39,000,000
Customer Relationships [Member] | Fiscal Year 2018 Acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles											10,200,000
In Process Research and Development [Member] | Fiscal Year 2020 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] | Horizon Discovery Group plc [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	10,800,000								10,800,000
Diagnostics [Member]
Business Acquisition [Line Items]
Goodwill	1,691,227,000				1,612,407,000				1,691,227,000	1,612,407,000	1,617,616,000
Discovery & Analytical Solutions [Member]
Business Acquisition [Line Items]
Goodwill	$ 1,755,887,000				1,498,820,000				1,755,887,000	1,498,820,000	1,334,992,000
United States of America, Dollars | Fiscal Year 2020 Other Acquisitions [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Cash Paid Including Working Capital And Other Adjustments									39,300,000
United States of America, Dollars | Horizon Discovery Group plc [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Cash Paid Including Working Capital And Other Adjustments									399,400,000
United States of America, Dollars | Fiscal Year 2020 Acquisitions [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Cash Paid Including Working Capital And Other Adjustments									438,700,000
United States of America, Dollars | Fiscal Year 2019 Acquisitions [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Cash Paid Including Working Capital And Other Adjustments										433,100,000
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High					$ 31,800,000					31,800,000
United States of America, Dollars | Fiscal Year 2019 Other Acquisitions [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Cash Paid Including Working Capital And Other Adjustments										46,600,000
United States of America, Dollars | Shandong Meizheng [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Cash Paid Including Working Capital And Other Adjustments										166,500,000
United States of America, Dollars | Cisbio Bioassays SAS [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Cash Paid Including Working Capital And Other Adjustments										$ 219,900,000
United States of America, Dollars | Fiscal Year 2018 Acquisitions [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Cash Paid Including Working Capital And Other Adjustments											$ 105,800,000
United Kingdom, Pounds | Horizon Discovery Group plc [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Cash Paid Including Working Capital And Other Adjustments									$ 296,000,000.0