REVENUE FROM CONTRACTS WITH CUSTOMERS - Disaggregation of Revenues by Major Business Line (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 30, 2023	Dec. 31, 2022	Dec. 25, 2021
Disaggregation of Revenue [Line Items]
Revenue	$ 4,129,409	$ 3,976,060	$ 3,540,160
RMS
Disaggregation of Revenue [Line Items]
Revenue	792,343	739,175	690,437
RMS | Services and products transferred over time
Disaggregation of Revenue [Line Items]
Revenue	377,947	340,708	263,659
RMS | Services and products transferred at a point in time
Disaggregation of Revenue [Line Items]
Revenue	414,396	398,467	426,778
DSA
Disaggregation of Revenue [Line Items]
Revenue	2,615,623	2,447,316	2,107,231
DSA | Services and products transferred over time
Disaggregation of Revenue [Line Items]
Revenue	2,611,564	2,440,646	2,103,415
DSA | Services and products transferred at a point in time
Disaggregation of Revenue [Line Items]
Revenue	4,059	6,670	3,816
Manufacturing
Disaggregation of Revenue [Line Items]
Revenue	721,443	789,569	742,492
Manufacturing | Services and products transferred over time
Disaggregation of Revenue [Line Items]
Revenue	381,942	371,500	335,745
Manufacturing | Services and products transferred at a point in time
Disaggregation of Revenue [Line Items]
Revenue	$ 339,501	$ 418,069	$ 406,747