SEGMENT INFORMATION - Revenue Per Significant Product or Service (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 28, 2020	Mar. 30, 2019
Segment Reporting Information [Line Items]
Total revenue	$ 707,059	$ 604,569
RMS
Segment Reporting Information [Line Items]
Total revenue	145,996	137,172
DSA
Segment Reporting Information [Line Items]
Total revenue	438,683	354,197
Manufacturing
Segment Reporting Information [Line Items]
Total revenue	$ 122,380	$ 113,200

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045

Name:	us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration