BUSINESS ACQUISITIONS - Narrative (Details) - USD ($) $ in Thousands				3 Months Ended
	Jan. 03, 2020	Aug. 28, 2019	Apr. 29, 2019	Mar. 28, 2020	Mar. 30, 2019	Dec. 28, 2019
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				$ 5,700
Actual revenue from acquiree				12,300
Operating income (loss) from acquiree				(2,200)
Citoxlab
Business Acquisition [Line Items]
Purchase price			$ 527,100
Purchase price allocation			490,357
Cash acquired			36,700
Integration related costs and transaction costs				1,400	$ 5,200
Actual revenue from acquiree				45,300	2,500
Goodwill, amount expected to be deductible for tax purposes			$ 7,200
Other Acquisitions
Business Acquisition [Line Items]
Purchase price		$ 23,400
Purchase price allocation		23,063
Cash acquired		300
Integration related costs and transaction costs				0
Prepayments for future purchases and other post-closing adjustments		$ 4,000
Depreciation and Amortization Expense | HemaCare Corporation
Business Acquisition [Line Items]
Adjustments related to prior period				$ 200	3,200
Depreciation and Amortization Expense | Citoxlab
Business Acquisition [Line Items]
Adjustments related to prior period					2,600
Interest Expense | HemaCare Corporation
Business Acquisition [Line Items]
Adjustments related to prior period					2,800
Interest Expense | Citoxlab
Business Acquisition [Line Items]
Adjustments related to prior period					$ 1,200
Supplier
Business Acquisition [Line Items]
Equity interest						80.00%
Noncontrolling interest ownership percentage						20.00%
Supplier | Other Acquisitions
Business Acquisition [Line Items]
Equity interest		80.00%
Noncontrolling interest ownership percentage		20.00%