BUSINESS COMBINATIONS - Narrative (Details) $ in Thousands, £ in Millions								3 Months Ended		12 Months Ended
	Mar. 30, 2021 USD ($)	Mar. 30, 2021 GBP (£)	Mar. 29, 2021 USD ($)	Mar. 03, 2021 USD ($)	Dec. 31, 2020 USD ($)	Aug. 06, 2020 USD ($)	Jan. 03, 2020 USD ($)	Mar. 27, 2021 USD ($)	Mar. 28, 2020 USD ($)	Dec. 26, 2020 USD ($)
Business Acquisition [Line Items]
Goodwill								$ 1,890,630		$ 1,809,168
Retrogenix Limited
Business Acquisition [Line Items]
Integration related costs and transaction costs								800
Retrogenix Limited | Subsequent Event
Business Acquisition [Line Items]
Purchase price	$ 48,000	£ 35
Consideration contingent upon future performance	$ 7,000	£ 5
Cognate BioServices, Inc.
Business Acquisition [Line Items]
Integration related costs and transaction costs								7,200
Cognate BioServices, Inc. | Subsequent Event
Business Acquisition [Line Items]
Purchase price			$ 875,000
Distributed Bio, Inc.
Business Acquisition [Line Items]
Purchase price					$ 97,000
Consideration contingent upon future performance					21,000
Contingent consideration liability					14,000
Purchase price allocation					97,030
Cash acquired					800
Integration related costs and transaction costs								700
Cash portion of consideration transferred					80,800
Payments to settle promissory note					3,000
Goodwill					$ 71,585
Weighted-average amortization life					7 years
Definite-lived intangible assets					$ 24,540
Property, plant and equipment					$ 2,382
Cellero, LLC
Business Acquisition [Line Items]
Purchase price						$ 37,400
Purchase price allocation						36,850
Cash acquired						500
Integration related costs and transaction costs								400
Goodwill, amount expected to be deductible for tax purposes						10,800
Goodwill						$ 19,457
Weighted-average amortization life						12 years
Definite-lived intangible assets						$ 16,230
Property, plant and equipment						$ 1,648
HemaCare Corporation
Business Acquisition [Line Items]
Purchase price							$ 379,800
Purchase price allocation							376,721
Cash acquired							3,100
Integration related costs and transaction costs								$ 100	$ 5,700
Goodwill							$ 210,196
Weighted-average amortization life							18 years
Definite-lived intangible assets							$ 183,540
Property, plant and equipment							$ 10,033
Other Acquisitions
Business Acquisition [Line Items]
Purchase price				$ 35,600
Contingent consideration liability				15,900
Cash portion of consideration transferred				19,700						$ 5,500
Goodwill				17,300
Definite-lived intangible assets				15,200
Property, plant and equipment				$ 3,000
Other Acquisitions | Supplier relationships
Business Acquisition [Line Items]
Weighted-average amortization life				4 years
Other Acquisitions | Maximum
Business Acquisition [Line Items]
Contingent consideration liability				$ 17,500
Depreciation and Amortization Expense | HemaCare Corporation
Business Acquisition [Line Items]
Adjustments related to prior period									$ 200