SEGMENT AND GEOGRAPHIC INFORMATION - Financial Information by Reportable Business Segment (Details) $ in Thousands	12 Months Ended
	Dec. 30, 2023 USD ($) segment	Dec. 31, 2022 USD ($)	Dec. 25, 2021 USD ($)
Segment Reporting [Abstract]
Number of reportable segments | segment	3
Segment Reporting Information [Line Items]
Revenue	$ 4,129,409	$ 3,976,060	$ 3,540,160
Operating income	617,261	650,975	589,862
Depreciation and amortization	314,124	303,870	265,540
Capital expenditures	318,528	324,733	228,772
Unallocated corporate
Segment Reporting Information [Line Items]
Operating income	(231,810)	(209,408)	(230,320)
Depreciation and amortization	3,853	2,181	2,968
Capital expenditures	2,684	3,950	7,230
RMS
Segment Reporting Information [Line Items]
Revenue	792,343	739,175	690,437
RMS | Operating Segments
Segment Reporting Information [Line Items]
Revenue	792,343	739,175	690,437
Operating income	154,666	160,410	166,814
Depreciation and amortization	55,570	49,274	39,123
Capital expenditures	52,819	44,136	61,188
DSA
Segment Reporting Information [Line Items]
Revenue	2,615,623	2,447,316	2,107,231
DSA | Operating Segments
Segment Reporting Information [Line Items]
Revenue	2,615,623	2,447,316	2,107,231
Operating income	606,076	532,889	406,978
Depreciation and amortization	174,719	179,465	177,254
Capital expenditures	204,891	189,563	101,477
Manufacturing
Segment Reporting Information [Line Items]
Revenue	721,443	789,569	742,492
Manufacturing | Operating Segments
Segment Reporting Information [Line Items]
Revenue	721,443	789,569	742,492
Operating income	88,329	167,084	246,390
Depreciation and amortization	79,982	72,950	46,195
Capital expenditures	$ 58,134	$ 87,084	$ 58,877