SEGMENT AND GEOGRAPHIC INFORMATION - Revenue by Product and Service Offering (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 25, 2021	Dec. 26, 2020	Dec. 28, 2019
Segment Reporting Information [Line Items]
Revenue	$ 3,540,160	$ 2,923,933	$ 2,621,226
RMS
Segment Reporting Information [Line Items]
Revenue	690,437	571,152	537,089
DSA
Segment Reporting Information [Line Items]
Revenue	2,107,231	1,837,428	1,618,995
Manufacturing
Segment Reporting Information [Line Items]
Revenue	$ 742,492	$ 515,353	$ 465,142