Charles River Laboratories International (CRL) 10-Q 4 May 21 2021 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 27, 2021	Apr. 23, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 27, 2021
Document Transition Report	false
Entity File Number	001-15943
Entity Registrant Name	CHARLES RIVER LABORATORIES INTERNATIONAL, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	06-1397316
Entity Address, Address Line One	251 Ballardvale Street
Entity Address, City or Town	Wilmington
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	01887
City Area Code	781
Local Phone Number	222-6000
Title of 12(b) Security	Common stock, $0.01 par value
Trading Symbol	CRL
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Smaller Reporting Company	false
Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		50,252,814
Entity Central Index Key	0001100682
Current Fiscal Year End Date	--12-25
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Amendment Flag	false

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Total revenue	$ 824,566	$ 707,059
Costs and expenses:
Selling, general and administrative	155,733	129,901
Amortization of intangible assets	28,842	27,879
Operating income	123,703	94,281
Other income (expense):
Interest income	35	316
Interest expense	(29,719)	(15,067)
Other expense, net	(27,717)	(24,071)
Income from operations, before income taxes	66,302	55,459
Provision for income taxes	2,367	4,622
Net income	63,935	50,837
Less: Net income attributable to noncontrolling interests	2,405	68
Net income attributable to common shareholders	$ 61,530	$ 50,769
Earnings per common share
Basic (in dollars per share)	$ 1.23	$ 1.03
Diluted (in dollars per share)	$ 1.20	$ 1.02
Weighted-average number of common shares outstanding:
Basic (in shares)	49,980	49,189
Diluted (in shares)	51,075	49,966
Service
Total revenue	$ 626,581	$ 546,592
Costs and expenses:
Cost of services provided and products sold (excluding amortization of intangible assets)	423,975	372,824
Product
Total revenue	197,985	160,467
Costs and expenses:
Cost of services provided and products sold (excluding amortization of intangible assets)	$ 92,313	$ 82,174

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 63,935	$ 50,837
Other comprehensive income (loss):
Foreign currency translation adjustment and other	9,829	(44,855)
Amortization of net loss and prior service benefit included in net periodic cost for pension and other post-retirement benefit plans	988	1,374
Comprehensive income, before income taxes	74,752	7,356
Less: Income tax benefit related to items of other comprehensive income	(1,025)	(2,039)
Comprehensive income, net of income taxes	75,777	9,395
Less: Comprehensive income (loss) related to noncontrolling interests, net of income taxes	2,390	(476)
Comprehensive income attributable to common shareholders, net of income taxes	$ 73,387	$ 9,871

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Thousands	Mar. 27, 2021	Dec. 26, 2020
Current assets:
Cash and cash equivalents	$ 465,411	$ 228,424
Trade receivables, net of allowances for doubtful accounts of $7,278 and $6,702, respectively	610,566	617,740
Inventories	193,584	185,695
Prepaid assets	81,726	96,712
Other current assets	71,922	72,560
Total current assets	1,423,209	1,201,131
Property, plant and equipment, net	1,117,003	1,124,358
Operating lease right-of-use assets, net	197,668	178,220
Goodwill	1,890,630	1,809,168
Client relationships and other intangible assets, net	795,565	787,599
Deferred tax assets	35,457	37,729
Other assets	349,431	352,626
Total assets	5,808,963	5,490,831
Current liabilities:
Current portion of long-term debt and finance leases	2,932	50,214
Accounts payable	127,129	122,475
Accrued compensation	164,748	206,823
Deferred revenue	213,032	207,942
Accrued liabilities	198,188	149,820
Other current liabilities	97,347	102,477
Total current liabilities	803,376	839,751
Long-term debt, net and finance leases	2,202,334	1,929,571
Operating lease right-of-use liabilities	173,015	155,595
Deferred tax liabilities	207,011	217,031
Other long-term liabilities	207,008	205,215
Total liabilities	3,592,744	3,347,163
Commitments and contingencies (Notes 2, 9, 11, 12, 16 and 17)
Redeemable noncontrolling interests	28,035	25,499
Equity:
Preferred stock, $0.01 par value; 20,000 shares authorized; no shares issued and outstanding	0	0
Common stock, $0.01 par value; 120,000 shares authorized; 50,350 shares issued and 50,216 shares outstanding as of March 27, 2021, and 49,767 shares issued and outstanding as of December 26, 2020	504	498
Additional paid-in capital	1,659,524	1,627,564
Retained earnings	686,944	625,414
Treasury stock, at cost, 134 and 0 shares, as of March 27, 2021 and December 26, 2020, respectively	(36,028)	0
Accumulated other comprehensive loss	(127,017)	(138,874)
Total equity attributable to common shareholders	2,183,927	2,114,602
Noncontrolling interest	4,257	3,567
Total equity	2,188,184	2,118,169
Total liabilities, redeemable noncontrolling interests and equity	5,808,963	5,490,831
Client relationships, net
Current assets:
Client relationships and other intangible assets, net	712,384	721,505
Other intangible assets, net
Current assets:
Client relationships and other intangible assets, net	$ 83,181	$ 66,094

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) - USD ($) $ in Thousands	Mar. 27, 2021	Dec. 26, 2020
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 7,278	$ 6,702
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	20,000,000	20,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	120,000,000	120,000,000
Common stock, shares issued (in shares)	50,350,000	49,767,000
Common stock, shares outstanding (in shares)	50,216,000	49,767,000
Treasury stock, shares (in shares)	134,000	0

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Cash flows relating to operating activities
Net income	$ 63,935	$ 50,837
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	61,508	57,260
Stock-based compensation	13,189	10,960
Debt extinguishment and financing costs	26,907	0
Deferred income taxes	(9,125)	(2,973)
Loss on venture capital and strategic equity investments, net	16,719	12,035
Other, net	496	10,495
Changes in assets and liabilities:
Trade receivables, net	5,598	(32,136)
Inventories	(11,404)	4,076
Accounts payable	9,622	(10,003)
Accrued compensation	(37,360)	(45,245)
Deferred revenue	5,006	6,065
Customer contract deposits	(5,446)	4,454
Other assets and liabilities, net	30,584	2,765
Net cash provided by operating activities	170,229	68,590
Cash flows relating to investing activities
Acquisition of businesses and assets, net of cash acquired	(94,197)	(382,250)
Capital expenditures	(28,030)	(25,721)
Purchases of investments and contributions to venture capital investments	(16,550)	(7,121)
Proceeds from sale of investments	0	2,504
Other, net	781	(1,097)
Net cash used in investing activities	(137,996)	(413,685)
Cash flows relating to financing activities
Proceeds from long-term debt and revolving credit facility	1,954,011	1,409,793
Proceeds from exercises of stock options	19,612	22,608
Payments on long-term debt, revolving credit facility, and finance lease obligations	(1,714,195)	(925,109)
Purchase of treasury stock	(36,028)	(23,675)
Payment of debt extinguishment and financing costs	(28,680)	0
Other, net	0	(4,405)
Net cash provided by financing activities	194,720	479,212
Effect of exchange rate changes on cash, cash equivalents, and restricted cash	10,953	290
Net change in cash, cash equivalents, and restricted cash	237,906	134,407
Cash, cash equivalents, and restricted cash, beginning of period	233,119	240,046
Cash, cash equivalents, and restricted cash, end of period	471,025	374,453
Supplemental cash flow information:
Cash, cash equivalents, and restricted cash, end of period	$ 471,025	$ 374,453

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (UNAUDITED) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Total Equity Attributable to Common Shareholders	Noncontrolling Interest
Beginning balance (in shares) at Dec. 28, 2019		48,936				0
Beginning balance at Dec. 28, 2019	$ 1,637,828	$ 489	$ 1,531,785	$ 280,329	$ (178,019)	$ 0	$ 1,634,584	$ 3,244
Increase (Decrease) in Stockholders' Equity
Net income	51,168			50,769			50,769	399
Other comprehensive loss	(40,898)				(40,898)		(40,898)
Buy-out and contingent consideration recognition in connection with redeemable noncontrolling interest	(2,379)		(2,379)				(2,379)
Issuance of stock under employee compensation plans (in shares)		694
Issuance of stock under employee compensation plans	22,623	$ 7	22,616				22,623
Acquisition of treasury shares (in shares)						144
Acquisition of treasury shares	(23,675)					$ (23,675)	(23,675)
Stock-based compensation	10,960		10,960				10,960
Ending balance (in shares) at Mar. 28, 2020		49,630				144
Ending balance at Mar. 28, 2020	1,655,627	$ 496	1,562,982	331,098	(218,917)	$ (23,675)	1,651,984	3,643
Beginning balance (in shares) at Dec. 26, 2020		49,767				0
Beginning balance at Dec. 26, 2020	2,118,169	$ 498	1,627,564	625,414	(138,874)	$ 0	2,114,602	3,567
Increase (Decrease) in Stockholders' Equity
Net income	62,220			61,530			61,530	690
Other comprehensive loss	11,857				11,857		11,857
Adjustment of redeemable noncontrolling interest to redemption value	(835)		(835)				(835)
Issuance of stock under employee compensation plans (in shares)		583
Issuance of stock under employee compensation plans	19,612	$ 6	19,606				19,612
Acquisition of treasury shares (in shares)						134
Acquisition of treasury shares	(36,028)					$ (36,028)	(36,028)
Stock-based compensation	13,189		13,189				13,189
Ending balance (in shares) at Mar. 27, 2021		50,350				134
Ending balance at Mar. 27, 2021	$ 2,188,184	$ 504	$ 1,659,524	$ 686,944	$ (127,017)	$ (36,028)	$ 2,183,927	$ 4,257

BASIS OF PRESENTATION

BASIS OF PRESENTATION	3 Months Ended
	Mar. 27, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
BASIS OF PRESENTATION	BASIS OF PRESENTATION The accompanying condensed consolidated financial statements are unaudited and have been prepared by Charles River Laboratories International, Inc. (the Company) in accordance with accounting principles generally accepted in the United States (U.S. GAAP) and pursuant to the rules and regulations of the Securities and Exchange Commission (SEC). The year-end condensed consolidated balance sheet data was derived from the Company’s audited consolidated financial statements, but does not include all disclosures required by U.S. GAAP. These unaudited condensed consolidated financial statements should be read in conjunction with the Company’s Annual Report on Form 10-K for fiscal year 2020. The unaudited condensed consolidated financial statements, in the opinion of management, reflect all normal and recurring adjustments necessary for a fair statement of the Company’s financial position and results of operations. Use of Estimates The preparation of unaudited condensed consolidated financial statements in accordance with U.S. GAAP requires that the Company make estimates and judgments that may affect the reported amounts of assets, liabilities, revenues, expenses and related disclosure of contingent assets and liabilities. On an on-going basis, the Company evaluates its estimates, judgments, and methodologies. The Company bases its estimates on historical experience and on various other assumptions that are believed to be reasonable, the results of which form the basis for making judgments about the carrying values of assets and liabilities. Actual results may differ from these estimates under different assumptions or conditions. Changes in estimates are reflected in reported results in the period in which they become known. On March 11, 2020, the World Health Organization declared the outbreak of a strain of novel coronavirus disease, COVID-19, a global pandemic. The COVID-19 pandemic is dynamic, and its ultimate scope, duration and effects are uncertain. This pandemic has and continues to result in, and any future epidemic or pandemic crises may potentially result in, direct and indirect adverse effects on the Company’s industry and customers, which in turn has (with respect to COVID-19) and may (with respect to future epidemics or crises) impact the Company’s business, results of operations and financial condition. Further, the COVID-19 pandemic may also affect the Company’s operating and financial results in a manner that is not presently known to the Company or that the Company currently does not expect to present significant risks to its operations or financial results. As of the date of issuance of these unaudited condensed consolidated financial statements, the Company is not aware of any specific event or circumstance that would require the Company to update estimates, judgments or revise the carrying value of any assets or liabilities. These estimates may change, as new events occur and additional information is obtained, and are recognized in the condensed consolidated financial statements as soon as they become known. Actual results could differ from those estimates and any such differences may be material to the Company’s condensed consolidated financial statements. Consolidation The Company’s unaudited condensed consolidated financial statements reflect its financial statements and those of its subsidiaries in which the Company holds a controlling financial interest. For consolidated entities in which the Company owns or is exposed to less than 100% of the economics, the Company records net income (loss) attributable to noncontrolling interests in its consolidated statements of income equal to the percentage of the economic or ownership interest retained in such entities by the respective noncontrolling parties. Intercompany balances and transactions are eliminated in consolidation. The Company’s fiscal year is typically based on 52-weeks, with each quarter composed of 13 weeks ending on the last Saturday on, or closest to, March 31, June 30, September 30, and December 31. Segment Reporting The Company reports its results in three reportable segments: Research Models and Services (RMS), Discovery and Safety Assessment (DSA), and Manufacturing Support (Manufacturing). The Company’s RMS reportable segment includes the Research Models, Research Model Services, and Research Products businesses. Research Models includes the commercial production and sale of small research models, as well as the supply of large research models. Research Model Services includes: Genetically Engineered Models and Services (GEMS), which performs contract breeding and other services associated with genetically engineered models; Research Animal Diagnostic Services (RADS), which provides health monitoring and diagnostics services related to research models; and Insourcing Solutions (IS), which provides colony management of its clients’ research operations (including recruitment, training, staffing, and management services). Research Products supplies controlled, consistent, customized primary cells and blood components derived from normal and mobilized peripheral blood, bone marrow, and cord blood. The Company’s DSA reportable segment includes services required to take a drug through the early development process including discovery services, which are non-regulated services to assist clients with the identification, screening, and selection of a lead compound for drug development, and regulated and non-regulated (GLP and non-GLP) safety assessment services. The Company’s Manufacturing reportable segment includes Microbial Solutions, which provides in vitro (non-animal) lot-release testing products, microbial detection products, and species identification services; Biologics Testing Services (Biologics), which performs specialized testing of biologics; and Avian Vaccine Services (Avian), which supplies specific-pathogen-free chicken eggs and chickens. Summary of Significant Accounting Policies The Company’s significant accounting policies are described in Note 1, “Description of Business and Summary of Significant Accounting Policies” in the Company’s Annual Report on Form 10-K for fiscal year 2020. Newly Adopted Accounting Pronouncements In January 2020, the Financial Accounting Standards Board (FASB) issue d ASU 2020-01, “Investments-Equity Securities (Topic 321), Investments-Equity Method and Joint Ventures (Topic 323), and Derivatives and Hedging (Topic 815).” ASU 2020-01 states any equity security transitioning from the alternative method of accounting under Topic 321 to the equity method, or vice versa, due to an observable transaction will be remeasured immediately before the transition. In addition, the ASU clarifies the accounting for certain non-derivative forward contracts or pur chased call options to acquire equity securities stating such instruments will be measured using the fair value principles of Topic 321 before settlement or exercise. This standard became effective for the Company in the three months ended March 27, 2021 and did not have a significant impact on the unaudited condensed consolidated financial statements and related disclosures. In December 2019, the FASB issued ASU 2019-12, “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes.” ASU 2019-12 simplifies the accounting for income taxes by removing exceptions within the general principles of Topic 740 regarding the calculation of deferred tax liabilities, the incremental approach for intraperiod tax allocation, and calculating income taxes in an interim period. In addition, the ASU adds clarifications to the accounting for franchise tax (or similar tax), which is partially based on income, evaluating tax basis of goodwill recognized from a business combination, and reflecting the effect of any enacted changes in tax laws or rates in the annual effective tax rate computation in the interim period that includes the enactment date. This standard became effective for the Company in the three months ended March 27, 2021 and did not have a significant impact on the unaudited condensed consolidated financial statements and related disclosures. Newly Issued Accounting Pronouncements In March 2020, the FASB issued ASU 2020-04, “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting.” The ASU , including subsequently issued updates, offers temp orary optional expedients and exceptions for applying U.S. GAAP to modifications to agreements such as loans, debt securities, derivatives, and borrowings which reference LIBOR or another reference rate that will partially discontinue after December 31, 2021 and fully cease by June 30, 2023. The expedients and exceptions provided by the standard do not apply to modifications made and hedging relationships entered into or evaluated after that, except for hedging relationships existing as of the phase-out date that an entity has elected certain optional expedients for and are retained through the end of the hedging relationship. The ASU is effective until the replacement for LIBOR is completed. The interest rate on the Company’s revolving credit facility, which was amended and restated in April 2021 (see Note 9. Long-term debt and finance lease obligations) matures in fiscal year 2026, is linked to LIBOR and alternative interest rates when LIBOR is discontinued. The Company is currently evaluating the impact this new standard will have on the consolidated financial statements and related disclosures, but does not believe there will be a material impact upon adoption.

BUSINESS COMBINATIONS

BUSINESS COMBINATIONS	3 Months Ended
	Mar. 27, 2021
Business Combinations [Abstract]
BUSINESS COMBINATIONS	BUSINESS COMBINATIONS Retrogenix Limited On March 30, 2021 (second fiscal quarter of 2021), the Company acquired Retrogenix Limited (Retrogenix) for approximately £35 million in cash (or approximately $48 million based on current exchange rates), subject to customary closing adjustments. In addition to the initial purchase price, the transaction includes a potential additional payment of up to £5 million based on future performance (or approximately $7 million based on current exchange rates). Retrogenix is an early-stage contract research organization providing specialized bioanalytical services utilizing its proprietary cell microarray technology. The acquisition of Retrogenix enhances the Company’s scientific expertise with additional large molecule and cell therapy discovery capabilities. The acquisition was funded through a combination of available cash and proceeds from the Company’s Credit Facility. This business will be reported as part of the Company’s DSA reportable segment. Due to the limited time between the acquisition date and the filing of this Quarterly Report on Form 10-Q, it is not practicable for the Company to disclose the preliminary allocation of the purchase price to assets acquired and liabilities assumed. The Company incurred transaction and integration costs in connection with the acquisition of $0.8 million during the three months ended March 27, 2021, which were included in Selling, general and administrative expenses within the unaudited condensed consolidated statements of income. Cognate BioServices, Inc. On March 29, 2021 (second fiscal quarter of 2021), the Company acquired Cognate BioServices, Inc. (Cognate BioServices) for approximately $875 million in cash, subject to customary closing adjustments. Cognate BioServices is a cell and gene therapy contract development and manufacturing organization (CDMO) offering comprehensive manufacturing solutions for cell therapies, as well as for the production of plasmid DNA and other inputs in the CDMO value chain. The acquisition of Cognate BioServices establishes the Company as a scientific partner for cell and gene therapy development, testing, and manufacturing, providing clients with an integrated solution from basic research and discovery through cGMP production. The acquisition was funded through a combination of available cash and proceeds from the Company’s Credit Facility and recently issued Senior Notes. This business will be reported as part of the Company’s Manufacturing reportable segment. Due to the limited time between the acquisition date and the filing of this Quarterly Report on Form 10-Q, it is not practicable for the Company to disclose either the preliminary allocation of the purchase price to assets acquired and liabilities assumed or the pro forma consolidated results of operations as if the Cognate BioServices acquisition had occurred as of the beginning of the period immediately preceding the period of acquisition after giving effect to certain adjustments. The Company incurred transaction and integration costs in connection with the acquisition of $7.2 million during the three months ended March 27, 2021, which were included in Selling, general and administrative expenses within the unaudited condensed consolidated statements of income. Distributed Bio, Inc. On December 31, 2020, the Company acquired Distributed Bio, Inc. (Distributed Bio), a next-generation antibody discovery company with technologies specializing in enhancing the probability of success for delivering high-quality, readily formattable antibody fragments to support antibody and cell and gene therapy candidates to biopharmaceutical clients. The acquisition of Distributed Bio expands the Company’s capabilities with an innovative, large-molecule discovery platform, and creates an integrated, end-to-end platform for therapeutic antibody and cell and gene therapy discovery and development. The preliminary purchase price of Distributed Bio was $97.0 million, net of $0.8 million in cash, subject to certain post-closing adjustments that may change the purchase price. The total consideration includes $80.8 million cash paid, settlement of $3.0 million in convertible promissory notes previously invested by the Company during prior fiscal years, and $14.0 million of contingent consideration, which is estimated using a Monte Carlo Simulation model (the maximum contingent contractual payments are up to $21.0 million based on future performance and milestone achievements over a one-year period). The acquisition was funded through a combination of available cash and proceeds from the Company’s Credit Facility. This business is reported as part of the Company’s DSA reportable segment. The preliminary purchase price allocation of $97.0 million, net of $0.8 million of cash acquired was as follows: December 31, 2020 (in thousands) Trade receivables $ 2,722 Other current assets (excluding cash) 221 Property, plant and equipment 2,382 Goodwill 71,585 Definite-lived intangible assets 24,540 Other long-term assets 2,055 Current liabilities (2,823) Deferred tax liabilities (2,529) Other long-term liabilities (1,123) Total purchase price allocation $ 97,030 The preliminary purchase price allocation is subject to change as additional information becomes available concerning the fair value and tax basis of the assets acquired and liabilities assumed, including certain contracts and obligations. Any additional adjustments to the purchase price allocation will be made as soon as practicable but no later than one year from the date of acquisition. The breakout of definite-lived intangible assets acquired was as follows: Definite-Lived Intangible Assets Weighted Average Amortization Life (in thousands) (in years) Client relationships $ 16,080 9 Developed technology 3,940 5 Other intangible assets 4,520 4 Total definite-lived intangible assets $ 24,540 7 The goodwill resulting from the transaction is primarily attributable to the potential growth of the Company’s DSA business from new customers introduced to Distributed Bio and the assembled workforce of the acquired business. The goodwill attributable to Distributed Bio is not deductible for tax purposes. The Company incurred transaction and integration costs in connection with the acquisition of $0.7 million during the three months ended March 27, 2021 , which were primarily included in Selling, general and administrative expenses within t he unaudited condensed consolidated statements of income. Pro forma financial information as well as the disclosure of actual revenue and operating income (loss) have not been included because Distributed Bio 's financial results are not significant when compared to the Company’s consolidated financial results. Cellero, LLC On August 6, 2020, the Company acquired Cellero, LLC (Cellero), a provider of cellular products for cell therapy developers and manufacturers worldwide. The addition of Cellero enhances the Company’s unique, comprehensive solutions for the high-growth cell therapy market, strengthening the ability to help accelerate clients’ critical programs from basic research and proof-of-concept to regulatory approval and commercialization. It also expands the Company’s access to high-quality, human-derived biomaterials with Cellero’s donor sites in the United States. The purchase price for Cellero was $37.4 million in cash . The acquisition was funded through available cash. This business is reported as part of the Company’s RMS reportable segment. The preliminary purchase price allocation of $36.9 million, net of $0.5 million of cash acquired was as follows: August 6, 2020 (in thousands) Trade receivables $ 1,500 Inventories 551 Other current assets (excluding cash) 182 Property, plant and equipment 1,648 Goodwill 19,457 Definite-lived intangible assets 16,230 Other long-term assets 849 Current liabilities (1,360) Deferred tax liabilities (1,467) Other long-term liabilities (740) Total purchase price allocation $ 36,850 The preliminary p urchase price allocation is subject to change as additional information becomes available concerning the fair value and tax basis of the assets acquired and liabilities assumed, including certain contracts and obligations. From the date of the acquisition through March 27, 2021, the Company recorded measurement-period adjustments related to the acquisition that resulted in an immaterial change to the purchase price allocation on a consolidated basis. Any additional adjustments to the purchase price allocation will be made as soon as practicable but no later than one year from the date of acquisition. The breakout of definite-lived intangible assets acquired was as follows: Definite-Lived Intangible Assets Weighted Average Amortization Life (in thousands) (in years) Client relationships $ 14,740 13 Other intangible assets 1,490 3 Total definite-lived intangible assets $ 16,230 12 The goodwill resulting from the transaction, $10.8 million of which is deductible for tax purposes due to a prior asset acquisition, is primarily attributable to the potential growth of the Company’s RMS business from customers introduced through Cellero and the assembled workforce of the acquired business. The Company incurred integration costs in connection with the acquisition of $0.4 million for the three months ended March 27, 2021, which were primarily included in Selling, general and administrative expenses within the unaudited condensed consolidated statements of income. Pro forma financial information as well as the disclosure of actual revenue and operating income (loss) have not been included because Cellero's financial results are not significant when compared to the Company’s consolidated financial results. HemaCare Corporation On January 3, 2020, the Company acquired HemaCare Corporation (HemaCare), a business specializing in the production of human-derived cellular products for the cell therapy market. The acquisition of HemaCare expands the Company’s comprehensive portfolio of early-stage research and manufacturing support solutions to encompass the production and customization of high-quality, human derived cellular products to better support clients’ cell therapy programs. The purchase price of HemaCare was $379.8 million in cash. The acquisition was funded through a combination of available cash and proceeds from the Company’s Credit Facility . This business is reported as part of the Company’s RMS reportable segment. The purchase price allocation of $376.7 million, net of $3.1 million of cash acquired was as follows: January 3, 2020 (in thousands) Trade receivables $ 6,451 Inventories 8,468 Other current assets (excluding cash) 3,494 Property, plant and equipment 10,033 Goodwill 210,196 Definite-lived intangible assets 183,540 Other long-term assets 5,920 Current liabilities (5,188) Deferred tax liabilities (38,529) Other long-term liabilities (7,664) Total purchase price allocation $ 376,721 From the date of the acquisition through December 26, 2020, the Company recorded measurement-period adjustments related to the acquisition that resulted in an immaterial change to the purchase price allocation on a consolidated basis. No further adjustments will be made to the purchase price allocation. The breakout of definite-lived intangible assets acquired was as follows: Definite-Lived Intangible Assets Weighted Average Amortization Life (in thousands) (in years) Client relationships $ 170,390 19 Trade name 7,330 10 Other intangible assets 5,820 3 Total definite-lived intangible assets $ 183,540 18 The goodwill resulting from the transaction is primarily attributable to the potential growth of the Company’s RMS business from customers introduced through HemaCare and the assembled workforce of the acquired business. The goodwill attributable to HemaCare is not deductible for tax purposes. The Company incurred transaction and integration costs in connection with the acquisition of $0.1 million and $5.7 million for the three months ended March 27, 2021 and March 28, 2020, respectively, which were primarily included in Selling, general and administrative expenses within the unaudited condensed consolidated statements of income. The following selected unaudited pro forma consolidated results of operations are presented as if the HemaCare acquisition had occurred as of the beginning of the p eriod immediately preceding the period of acquisition, which is December 30, 2018, after giving effect to certain adjustments. For t he three months ended March 28, 2020, these adjustments included additional amortization of intangible assets and depreciation of fixed assets of $0.2 million, elimi nation of intercompany activity and other one-time costs, and the tax impacts of these adjustments. Three Months Ended March 28, 2020 (in thousands) (unaudited) Revenue $ 707,077 Net income attributable to common shareholders 55,705 These unaudited pro forma results of operations have been prepared for comparative purposes only, and they do not purport to be indicative of the results of operations that actually would have resulted had the acquisition occurred on the dates indicated or that may result in the future. No effect has been given for synergies, if any, that may be realized through the acquisition. Other Acquisition On March 3, 2021, the Company acquired certain assets from a distributor that supports the Company’s DSA reportable segment. The preliminary purchase price was $35.6 million, which includes $19.7 million in cash paid ($5.5 million of which was paid in fiscal 2020), subject to customary closing adjustments, and $15.9 million of contingent consideration, which is

REVENUE FROM CONTRACTS WITH CUS

REVENUE FROM CONTRACTS WITH CUSTOMERS	3 Months Ended
	Mar. 27, 2021
Revenue from Contract with Customer [Abstract]
REVENUE FROM CONTRACTS WITH CUSTOMERS	REVENUE FROM CONTRACTS WITH CUSTOMERS Disaggregation of Revenue The following table disaggregates the Company’s revenue by major business line and timing of transfer of products or services: Three Months Ended March 27, 2021 March 28, 2020 (in thousands) Timing of Revenue Recognition: RMS Services and products transferred over time $ 64,896 $ 60,041 Services and products transferred at a point in time 112,014 85,955 Total RMS revenue 176,910 145,996 DSA Services and products transferred over time 500,468 438,564 Services and products transferred at a point in time 710 119 Total DSA revenue 501,178 438,683 Manufacturing Services and products transferred over time 50,568 37,314 Services and products transferred at a point in time 95,910 85,066 Total Manufacturing revenue 146,478 122,380 Total revenue $ 824,566 $ 707,059 RMS The RMS business generates revenue through the commercial production and sale of research models, research products, and the provision of services related to the maintenance and monitoring of research models and management of clients’ research operations. Revenue from the sale of research models and products is recognized at a point in time when the customer obtains control of the product, which may be upon shipment or upon delivery based on the shipping terms of a contract. Revenue generated from research models services is recognized over time and is typically based on a right-to-invoice measure of progress (output method) as invoiced amounts correspond directly to the value of the Company’s performance to date. DSA The Discovery and Safety Assessment business provides a full suite of integrated drug discovery services directed at the identification, screening and selection of a lead compound for drug development and offers a full range of safety assessment services including bioanalysis, drug metabolism, pharmacokinetics, toxicology and pathology. Discovery and Safety Assessment services revenue is generally recognized over time using the cost-to-cost or right to invoice measures of progress, primarily representing fixed fee service contracts and per unit service contracts, respectively. Manufacturing The Manufacturing business includes Microbial Solutions, which provides in vitro (non-animal) lot-release testing products, microbial detection products, and species identification services; Biologics Testing Services (Biologics), which performs specialized testing of biologics; and Avian Vaccine Services (Avian), which supplies specific-pathogen-free chicken eggs and chickens. Species identification service revenue is generally recognized at a point in time as identifications are completed by the Company. Biologics service revenue is generally recognized over time using the cost-to-cost measure of progress. Microbial Solutions and Avian product sales are generally recognized at a point in time when the customer obtains control of the product, which may be upon shipment or upon delivery based on the contractual shipping terms of a contract. Transaction Price Allocated to Future Performance Obligations The Company discloses the aggregate amount of transaction price that is allocated to performance obligations that have not yet been satisfied as of March 27, 2021. Excluded from the disclosure is the value of unsatisfied performance obligations for (i) contracts with an original expected length of one year or less and (ii) contracts for which revenue is recognized at the amount to which the Company has the right to invoice for services performed. The Company has assessed future performance obligations with respect to the COVID-19 pandemic uncertainties and believes there is an insignificant impact on the ability to meet future performance obligations and the amount of revenue to be recognize d. The following table inclu des estimated revenue expected to be recognized in the future related to performance obligations that are unsatisfied (or partially satisfied) as of March 27, 2021: Revenue Expected to be Recognized in Future Periods Less than 1 Year 1 to 3 Years 4 to 5 Years Beyond 5 Years Total (in thousands) DSA $ 212,919 $ 120,893 $ 4,404 $ 122 $ 338,338 Manufacturing 8,724 3,170 — — 11,894 Total $ 221,643 $ 124,063 $ 4,404 $ 122 $ 350,232 Contract Balances from Contracts with Customers The timing of revenue recognition, billings and cash collections results in billed receivables (client receivables), contract assets (unbilled revenue), and contract liabilities (current and long-term deferred revenue and customer contract deposits) on the unaudited condensed consolidated balance sheets. The Company’s payment terms are generally 30 days in the United States and consistent with prevailing practice in international markets. A contract asset is recorded when a right to consideration in exchange for goods or services transferred to a customer is conditioned other than the passage of time. Client receivables are recorded separately from contract assets since only the passage of time is required before consideration is due. A contract liability is recorded when consideration is received, or such consideration is unconditionally due, from a customer prior to transferring goods or services to the customer under the terms of a contract. Contract liabilities are recognized as revenue after control of the products or services is transferred to the customer and all revenue recognition criteria have been met. The following table provides information about client receivables, contract assets, and contract liabilities from contracts with customers: March 27, 2021 December 26, 2020 (in thousands) Balances from contracts with customers: Client receivables $ 463,800 $ 489,042 Contract assets (unbilled revenue) 154,044 135,400 Contract liabilities (current and long-term deferred revenue) 233,075 227,417 Contract liabilities (customer contract deposits) 36,652 42,244 When the Company does not have the unconditional right to advanced billings, both advanced client payments and unpaid advanced client billings are excluded from deferred revenue, with the advanced billings also being excluded from client receivables. The Company excluded approximately $19 million and $16 million of unpaid advanced client billings from both client receivables and deferred revenue in the accompanying unaudited condensed consolidated balance sheets as of March 27, 2021 and December 26, 2020, respectively. Advanced client payments of approximately $37 million and $42 million have been presented as customer contract deposits within other current liabilities in the accompanying unaudited condensed consolidated balance sheets as of March 27, 2021 and December 26, 2020, respectively. Other changes in the contract asset and the contract liability balances during the three months ended March 27, 2021 and March 28, 2020 were as follows: (i) Changes due to business combinations: See Note 2. “Business Combinations” for the Company’s recent acquisitions. (ii) Cumulative catch-up adjustments to revenue that affect the corresponding contract asset or contract liability, including adjustments arising from a change in the measure of progress, a change in an estimate of the transaction price (including any changes in the assessment of whether an estimate of variable consideration is constrained), or a contract modification: During the three months ended March 27, 2021 and March 28, 2020, immaterial cumulative catch-up adjustments to revenue were recorded. (iii) A change in the time frame for a right to consideration to become unconditional (that is, for a contract asset to be recorded as a client receivable): Approximatel y 60% of unbilled revenue as of December 26, 2020 was billed during the three months ended March 27, 2021. Approximately 60% of unbilled revenue as of December 28, 2019, which was $122 million, was billed during the three months ended March 28, 2020. (iv) A change in the time frame for a performance obligation to be satisfied (that is, for the recognition of revenue arising from a contract liability): Approximately 60% of contract liabilities as of December 26, 2020 were recognized as revenue during the three months ended March 27, 2021. Approximately 60% of contract liabilities as of December 28, 2019, which was $193 million, were recognized as revenue during the three months ended March 28, 2020.

SEGMENT INFORMATION

SEGMENT INFORMATION	3 Months Ended
	Mar. 27, 2021
Segment Reporting [Abstract]
SEGMENT INFORMATION	SEGMENT INFORMATION The Company’s three reportable segments are RMS, DSA, and Manufacturing. The following table presents revenue and other financial information by reportable segment: Three Months Ended March 27, 2021 March 28, 2020 (in thousands) RMS Revenue $ 176,910 $ 145,996 Operating income 44,935 27,373 Depreciation and amortization 9,679 8,752 Capital expenditures 2,983 5,412 DSA Revenue $ 501,178 $ 438,683 Operating income 90,949 72,283 Depreciation and amortization 44,608 41,330 Capital expenditures 17,040 14,729 Manufacturing Revenue $ 146,478 $ 122,380 Operating income 49,437 41,112 Depreciation and amortization 6,569 6,366 Capital expenditures 7,110 5,161 Reconciliations of segment operating income, depreciation and amortization, and capital expenditures to the respective consolidated amounts are as follows: Operating Income Depreciation and Amortization Capital Expenditures March 27, 2021 March 28, 2020 March 27, 2021 March 28, 2020 March 27, 2021 March 28, 2020 (in thousands) Three Months Ended: Total reportable segments $ 185,321 $ 140,768 $ 60,856 $ 56,448 $ 27,133 $ 25,302 Unallocated corporate (61,618) (46,487) 652 812 897 419 Total consolidated $ 123,703 $ 94,281 $ 61,508 $ 57,260 $ 28,030 $ 25,721 Revenue for each significant product or service offering is as follows: Three Months Ended March 27, 2021 March 28, 2020 (in thousands) RMS $ 176,910 $ 145,996 DSA 501,178 438,683 Manufacturing 146,478 122,380 Total revenue $ 824,566 $ 707,059 A summary of unallocated corporate expense consists of the following: Three Months Ended March 27, 2021 March 28, 2020 (in thousands) Stock-based compensation $ 7,642 $ 6,704 Compensation, benefits, and other employee-related expenses 27,362 21,980 External consulting and other service expenses 7,356 2,469 Information technology 4,095 3,716 Depreciation 652 812 Acquisition and integration 10,560 6,983 Other general unallocated corporate 3,951 3,823 Total unallocated corporate expense $ 61,618 $ 46,487 Other general unallocated corporate expense consists of costs associated with departments such as senior executives, corporate accounting, legal, tax, human resources, treasury, and investor relations. Revenue by geographic area is as follows: U.S. Europe Canada Asia Pacific Other Consolidated (in thousands) Three Months Ended: March 27, 2021 $ 448,482 $ 237,535 $ 77,107 $ 59,446 $ 1,996 $ 824,566 March 28, 2020 406,712 190,262 76,633 31,829 1,623 707,059 Included in the Other category above are operations located in Brazil and Israel. Revenue represents sales originating in entities physically located in the identified geographic area.

SUPPLEMENTAL BALANCE SHEET INFO

SUPPLEMENTAL BALANCE SHEET INFORMATION	3 Months Ended
	Mar. 27, 2021
Supplemental Balance Sheet Information [Abstract]
SUPPLEMENTAL BALANCE SHEET INFORMATION	SUPPLEMENTAL BALANCE SHEET INFORMATION The composition of trade receivables, net is as follows: March 27, 2021 December 26, 2020 (in thousands) Client receivables $ 463,800 $ 489,042 Unbilled revenue 154,044 135,400 Total 617,844 624,442 Less: Allowance for doubtful accounts (7,278) (6,702) Trade receivables, net $ 610,566 $ 617,740 The composition of inventories is as follows: March 27, 2021 December 26, 2020 (in thousands) Raw materials and supplies $ 26,726 $ 28,317 Work in process 32,619 36,755 Finished products 134,239 120,623 Inventories $ 193,584 $ 185,695 The composition of other current assets is as follows: March 27, 2021 December 26, 2020 (in thousands) Prepaid income tax $ 66,885 $ 68,462 Short-term investments 1,025 1,024 Restricted cash 4,012 3,074 Other current assets $ 71,922 $ 72,560 The composition of other assets is as follows: March 27, 2021 December 26, 2020 (in thousands) Venture capital investments $ 175,506 $ 197,100 Strategic equity investments 35,772 24,704 Life insurance policies 46,258 43,827 Other long-term income tax assets 22,827 23,485 Restricted cash 1,602 1,621 Long-term pension assets 33,435 31,915 Other 34,031 29,974 Other assets $ 349,431 $ 352,626 The composition of other current liabilities is as follows: March 27, 2021 December 26, 2020 (in thousands) Current portion of operating lease right-of-use liabilities $ 25,868 $ 24,674 Accrued income taxes 24,952 24,884 Customer contract deposits 36,652 42,244 Other 9,875 10,675 Other current liabilities $ 97,347 $ 102,477 The composition of other long-term liabilities is as follows: March 27, 2021 December 26, 2020 (in thousands) U.S. Transition Tax $ 48,781 $ 48,781 Long-term pension liability, accrued executive supplemental life insurance retirement plan and deferred compensation plan 74,223 74,233 Long-term deferred revenue 20,043 19,475 Other 63,961 62,726 Other long-term liabilities $ 207,008 $ 205,215

VENTURE CAPITAL AND STRATEGIC E

VENTURE CAPITAL AND STRATEGIC EQUITY INVESTMENTS	3 Months Ended
	Mar. 27, 2021
Equity Method Investments and Joint Ventures [Abstract]
VENTURE CAPITAL AND STRATEGIC EQUITY INVESTMENTS	VENTURE CAPITAL AND STRATEGIC EQUITY INVESTMENTS Venture capital investments were $175.5 million and $197.1 million as of March 27, 2021 and December 26, 2020, respectively. The Company’s total commitment to the venture capital funds as of March 27, 2021 was $149.3 million, of which the Company funded $99.7 million through that date. The Company received distributions totaling $9.3 million and $0.9 million for the three months ended March 27, 2021 and March 28, 2020, respectively. The Company recognized net losses of $16.4 million and $12.2 million related to the venture capital investments for the three months ended March 27, 2021 and March 28, 2020, respectively, primarily driven by decreases in fair value of publicly-held investments. The Company also invests, with minority positions, directly in equity of predominantly privately-held companies. Strategic equity investments were $35.8 million and $24.7 million as of March 27, 2021 and December 26, 2020, respectively. The Company recognized insignificant gains and losses for the three months ended March 27, 2021 and March 28, 2020, respectively.

FAIR VALUE

FAIR VALUE	3 Months Ended
	Mar. 27, 2021
Fair Value Disclosures [Abstract]
FAIR VALUE	FAIR VALUEThe Company has certain financial assets and liabilities recorded at fair value, which have been classified as Level 1, 2, or 3 within the fair value hierarchy: • Level 1 - Fair values are determined utilizing prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access, • Level 2 - Fair values are determined by utilizing quoted prices for identical or similar assets and liabilities in active markets or other market observable inputs such as interest rates, yield curves, and foreign currency spot rates, • Level 3 - Prices or valuations that require inputs that are both significant to the fair value measurement and unobservable. The fair value hierarchy level is determined by asset and class based on the lowest level of significant input. The observability of inputs may change for certain assets or liabilities. This condition could cause an asset or liability to be reclassified between levels. The Company recognizes transfers between levels within the fair value hierarchy, if any, at the end of each quarter. During the three months ended March 27, 2021 and March 28, 2020, there were no transfers between levels. Valuation methodologies used for assets and liabilities measured or disclosed at fair value are as follows: • Cash equivalents - Valued at market prices determined through third-party pricing services; • Foreign currency forward contracts - Valued using market observable inputs, such as forward foreign exchange points and foreign exchanges rates; • Life insurance policies - Valued at cash surrender value based on the fair value of underlying investments; • Debt instruments - The book value of the Company’s term and revolving loans, which are variable rate loans carried at amortized cost, approximates the fair value based on current market pricing of similar debt. The book values of the Company’s Senior Notes, which are fixed rate debt, are carried at amortized cost. Fair values of the Senior Notes are based on quoted market prices and on borrowing rates available to the Company; and • Contingent consideration - Valued based on a probability weighting of the future cash flows associated with the potential outcomes. Assets and liabilities measured at fair value on a recurring basis are summarized below: March 27, 2021 Level 1 Level 2 Level 3 Total (in thousands) Cash equivalents $ — $ 6,172 $ — $ 6,172 Other assets: Life insurance policies — 38,250 — 38,250 Total assets measured at fair value $ — $ 44,422 $ — $ 44,422 Other liabilities measured at fair value: Contingent consideration $ — $ — $ 33,163 $ 33,163 Total liabilities measured at fair value $ — $ — $ 33,163 $ 33,163 December 26, 2020 Level 1 Level 2 Level 3 Total (in thousands) Cash equivalents $ — $ 2,273 $ — $ 2,273 Other assets: Life insurance policies — 35,770 — 35,770 Total assets measured at fair value $ — $ 38,043 $ — $ 38,043 Other liabilities measured at fair value: Contingent consideration $ — $ — $ 2,328 $ 2,328 Total liabilities measured at fair value $ — $ — $ 2,328 $ 2,328 Contingent Consideration The following table provides a rollforward of the contingent consideration related to the Company’s business combinations. See Note 2, “Business Combinations.” Three Months Ended March 27, 2021 March 28, 2020 (in thousands) Beginning balance $ 2,328 $ 712 Additions 29,990 2,131 Fair value adjustments 917 — Payments — (218) Foreign currency (72) (62) Ending balance $ 33,163 $ 2,563 The Company estimates the fair value of contingent consideration obligations through valuation models, such as probability-weighted and option pricing models, that incorporate probability adjusted assumptions and simulations related to the achievement of the milestones and the likelihood of making related payments. The unobservable inputs used in the fair value measurements include the probabilities of successful achievement of certain financial targets, forecasted results or targets, volatilities, discount rates, and risk-free rates. Increases or decreases in these assumptions may result in a higher or lower fair value measurement, respectively. Debt Instruments The book value of the Company’s term and revolving loans, which are variable rate loans carried at amortized cost, approximates the fair value based on current market pricing of similar debt. As the fair value is based on significant other observable inputs, including current interest and foreign currency exchange rates, it is deemed to be Level 2 within the fair value hierarchy. The book value of the Company’s Senior Notes are fixed rate obligations carried at amortized cost. Fair value is based on quoted market prices as well as borrowing rates available to the Company. As the fair value is based on significant other observable outputs, it is deemed to be Level 2 within the fair value hierarchy. The book value and fair value of the Company’s Senior Notes is summarized below: March 27, 2021 December 26, 2020 Book Value Fair Value Book Value Fair Value 5.5% Senior Notes due 2026 $ — $ — $ 500,000 $ 523,100 4.25% Senior Notes due 2028 500,000 513,750 500,000 523,750 3.75% Senior Notes due 2029 500,000 501,250 — — 4.0% Senior Notes due 2031 500,000 504,350 — —

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS	3 Months Ended
	Mar. 27, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND INTANGIBLE ASSETS	GOODWILL AND INTANGIBLE ASSETS Goodwill The following table provides a rollforward of the Company’s goodwill: Adjustments to Goodwill December 26, 2020 Acquisitions Foreign Exchange March 27, 2021 (in thousands) RMS $ 287,759 $ — $ (169) $ 287,590 DSA 1,378,130 88,611 (7,726) 1,459,015 Manufacturing 143,279 — 746 144,025 Goodwill $ 1,809,168 $ 88,611 $ (7,149) $ 1,890,630 The increase in goodwill during the three months ended March 27, 2021 related primarily to the acquisition of Distributed Bio in the DSA reportable segment. Intangible Assets, Net The following table displays intangible assets, net by major class: March 27, 2021 December 26, 2020 Gross Accumulated Amortization Net Gross Accumulated Amortization Net (in thousands) Backlog $ 610 $ (152) $ 458 $ 29,233 $ (29,233) $ — Technology 133,667 (85,610) 48,057 130,907 (81,305) 49,602 Trademarks and trade names 12,231 (2,112) 10,119 15,870 (5,648) 10,222 Other 28,736 (4,189) 24,547 20,903 (14,633) 6,270 Other intangible assets 175,244 (92,063) 83,181 196,913 (130,819) 66,094 Client relationships 1,152,499 (440,115) 712,384 1,137,331 (415,826) 721,505 Intangible assets $ 1,327,743 $ (532,178) $ 795,565 $ 1,334,244 $ (546,645) $ 787,599 The increase in intangible assets, net during the three months ended March 27, 2021 related primarily to the acquisition of Distributed Bio.

LONG-TERM DEBT AND FINANCE LEAS

LONG-TERM DEBT AND FINANCE LEASE OBLIGATIONS	3 Months Ended
	Mar. 27, 2021
Debt Disclosure [Abstract]
LONG-TERM DEBT AND FINANCE LEASE OBLIGATIONS	LONG-TERM DEBT AND FINANCE LEASE OBLIGATIONS Long-term debt, net and finance leases consists of the following: March 27, 2021 December 26, 2020 (in thousands) Term loans $ — $ 146,875 Revolving facility 694,135 814,752 5.5% Senior Notes due 2026 — 500,000 4.25% Senior Notes due 2028 500,000 500,000 3.75% Senior Notes due 2029 500,000 — 4.0% Senior Notes due 2031 500,000 — Other debt 369 3,457 Finance leases (Note 16) 28,844 29,047 Total debt and finance leases 2,223,348 1,994,131 Less: Current portion of long-term debt 109 47,196 Current portion of finance leases (Note 16) 2,823 3,018 Current portion of long-term debt and finance leases 2,932 50,214 Long-term debt and finance leases 2,220,416 1,943,917 Debt discount and debt issuance costs (18,082) (14,346) Long-term debt, net and finance leases $ 2,202,334 $ 1,929,571 As of March 27, 2021 and December 26, 2020, the weighted average interest rate on the Company’s debt was 3.09% and 3.11%, respectively. Term L oans and Revolving Facility (Credit Facility) As of and for the three months ended March 27, 2021, the Company had a credit facility consisting of a $750 million term loan and a $2.05 billion multi-currency revolving facility. The term loan facility matured in 19 quarterly installments with the last installment due March 26, 2023. During the three months ended March 27, 2021, the Company prepaid the remaining amount of the term loan, or $146.9 million, with proceeds from an unregistered private offering (see 2029 and 2031 Senior Notes below). The revolving facility matured on March 26, 2023, and required no scheduled payment before that date. Approximately $0.2 million of deferred financing costs were expensed upon prepayment of the term loan. The interest rates applicable to the term loan and revolving facility under the Credit Facility were, at the Company’s option, equal to either the base rate (which is the higher of (1) the prime rate, (2) the federal funds rate plus 0.50%, or (3) the one- month adjusted LIBOR rate plus 1.0%) or the adjusted LIBOR rate, plus an interest rate margin based upon the Company’s leverage ratio. In April 2021, the Company amended and restated the Credit Facility increasing the capacity of the revolving credit facility and extending the maturity date to April 2026, which requires no scheduled payment before that date. The amended and restated Credit Facility provides for a $3.0 billion multi-currency revolving facility. No additional term loan was borrowed. Certain amendments were made in connection with the prospective discontinuation of LIBOR and certain other changes in law since the execution of the Company’s existing credit agreement and makes certain other amendments to certain other covenants and terms. The interest rates applicable to the amended and restated revolving facility are equal to (A) for revolving loans denominated in U.S. dollars, at the Company’s option, either the base rate (which is the higher of (1) the prime rate, (2) the federal funds rate plus 0.50%, or (3) the one-month adjusted LIBOR rate plus 1%) or the adjusted LIBOR rate, (B) for revolving loans denominated in euros, the adjusted EURIBOR rate and (C) for revolving loans denominated in sterling, the daily simple SONIA rate, in each case, plus an interest rate margin based upon the Company’s leverage ratio. The Credit Facility includes certain customary representations and warranties, events of default, notices of material adverse changes to the Company’s business and negative and affirmative covenants. These covenants include (1) maintenance of a ratio of consolidated earnings before interest, taxes, depreciation and amortization (EBITDA) less capital expenditures to consolidated cash interest expense, for any period of four consecutive fiscal quarters, of no less than 3.50 to 1.0 as well as (2) maintenance of a ratio of consolidated indebtedness to consolidated EBITDA for any period of four consecutive fiscal quarters, of no more than 4.25 to 1.0. As of March 27, 2021, the Company was compliant with all covenants under the Credit Agreement. The obligations of the Company under the Credit Facility are collateralized by substantially all of the assets of the Company. During the three months ended March 27, 2021 and March 28, 2020, the Company had multiple U.S. dollar denominated loans borrowed by a non-U.S. Euro functional currency entity under the Company’s Credit Facilit y, which ranged from $300 million to $400 million each. This resulted in foreign currency losses recognized in Other income, net of $13.4 million and $4.2 million during the three months ended March 27, 2021 and March 28, 2020, respectively, related to the remeasurement of the underlying debt. The Company entered into foreign exchange forward contracts to limit its foreign currency ex posures related to these borrowings and recognized gains of $14.0 million and $6.1 million during the three months ended March 27, 2021 and March 28, 2020, respectively, within Interest expense. As of March 27, 2021, the Company did not have any outstanding borrowings in a currency different than its respective functional currency. Se e Note 14, “Foreign Currency Contracts”, for further discussion. Base Indenture for Senior Notes The Company enters into certain indentures in order to issue senior notes and is subject to certain affirmative and negative covenants. The Company has the following Senior Notes in the current and prior fiscal periods. 2026 Senior Notes In fiscal year 2018, the Company issued $500 million of 5.5% Senior Notes due in 2026 (2026 Senior Notes) in an unregistered offering. Interest on the 2026 Senior Notes was payable semi-annually on April 1 and October 1. On March 23, 2021, the Company prepaid the $500 million 2026 Seniors Notes along with $21 million of related debt extinguishment costs and $13 million of accrued interest using proceeds from additional senior notes issued on the same day (see 2029 and 2031 Senior Notes). The payment of the 2026 Senior Notes was accounted for as a debt extinguishment. Approximately $21 million of debt extinguishment costs and $5 million of deferred financing costs write-offs were recorded in Interest expense for the three months ended March 27, 2021. 2028 Senior Notes In fiscal year 2019, the Company issued $500 million of 4.25% Senior Notes due in 2028 (2028 Senior Notes) in an unregistered offering. Interest on the 2028 Senior Notes is payable semi-annually on May 1 and November 1. 2029 Senior Notes and 2031 Senior Notes In the three months ended March 27, 2021, the Company issued $1 billion split between $500 million of 3.75% Senior Notes due in 2029 (2029 Senior Notes), and $500 million of 4.00% Senior Notes due in 2031 (2031 Senior Notes), in an unregistered offering. Interest on the 2029 and 2031 Senior Notes is payable semi-annually on March 15 and September 15. Approximately $10 million of deferred financing costs were capitalized as part of this debt issuance. Proceeds from the 2029 and 2031 Senior Notes were used as follows: prepay the $500 million 2026 Senior Notes, $21 million of debt extinguishment costs, and $13 million of accrued interest; prepay the $146.9 million remaining term loan; pay down $135 million of the revolving facility; and pay for a portion of the Cognate BioServices acquisition, which occurred on March 29, 2021. Principal Maturities Principal maturities of existing debt, giving effect to the amended and restated Credit Agreement, for the periods set forth in the table below, are as follows: Principal (in thousands) 2021 (excluding the three months ended March 27, 2021) $ 109 2022 — 2023 — 2024 260 2025 — Thereafter 2,194,135 Total $ 2,194,504 Letters of Credit As of March 27, 2021 and December 26, 2020, the Company had $16.8 million and $16.0 million, respectively, in outstanding letters of credit.

EQUITY AND NONCONTROLLING INTER

EQUITY AND NONCONTROLLING INTERESTS	3 Months Ended
	Mar. 27, 2021
Equity [Abstract]
EQUITY AND NONCONTROLLING INTERESTS	EQUITY AND NONCONTROLLING INTERESTS Earnings Per Share The following table reconciles the numerator and denominator in the computations of basic and diluted earnings per share: Three Months Ended March 27, 2021 March 28, 2020 (in thousands) Numerator: Net income $ 63,935 $ 50,837 Less: Net income attributable to noncontrolling interests 2,405 68 Net income attributable to common shareholders $ 61,530 $ 50,769 Denominator: Weighted-average shares outstanding - Basic 49,980 49,189 Effect of dilutive securities: Stock options, restricted stock units and performance share units 1,095 777 Weighted-average shares outstanding - Diluted 51,075 49,966 Options to purchase less than 0.1 million and 0.4 million shares for the three months ended March 27, 2021 and March 28, 2020, respectively, as well as a non-significant number of restricted stock units (RSUs) and performance share units (PSUs), were not included in computing diluted earnings per share because their inclusion would have been anti-dilutive. Basic weighted-average shares outstanding for both the three months ended March 27, 2021 and March 28, 2020 excluded the impact of 0.6 million shares of non-vested RSUs and PSUs. Treasury Shares During the three months ended March 27, 2021 and March 28, 2020, the Company did not repurchase any shares under its authorized stock repurchase program. As of March 27, 2021, the Company had $129.1 million remaining on the authorized stock repurchase program. The Company’s stock-based compensation plans permit the netting of common stock upon vesting of RSUs and PSUs in order to satisfy individual statutory tax withholding requirements. During the three months ended March 27, 2021 and March 28, 2020, the Company acquired 0.1 million shares for $36.0 million and 0.1 million shares for $23.7 million, respectively, from such netting. Accumulated Other Comprehensive Income (Loss) Changes to each component of accumulated other comprehensive income (loss), net of income taxes, are as follows: Foreign Currency Translation Adjustment Pension and Other Post-Retirement Benefit Plans Total (in thousands) December 26, 2020 $ (73,884) $ (64,990) $ (138,874) Other comprehensive income before reclassifications 9,844 — 9,844 Amounts reclassified from accumulated other comprehensive income — 988 988 Net current period other comprehensive income 9,844 988 10,832 Income tax (benefit) expense (1,270) 245 (1,025) March 27, 2021 $ (62,770) $ (64,247) $ (127,017) Nonredeemable Noncontrolling Interest The Company has an investment in an entity whose financial results are consolidated in the Company’s unaudited condensed consolidated financial statements, as it has the ability to exercise control over this entity. The interest of the noncontrolling party in this entity has been recorded as noncontrolling interest within Equity in the accompanying unaudited condensed consolidated balance sheets. The activity within the nonredeemable noncontrolling interest was not significant during the three months ended March 27, 2021 and March 28, 2020. Redeemable Noncontrolling Interests The Company has a 92% equity interest in Vital River with an 8% redeemable noncontrolling interest. The Company has the right to purchase, and the noncontrolling interest holders have the right to sell, the remaining 8% equity interest at a contractually defined redemption value, subject to a redemption floor, which represents a derivative embedded within the equity instrument. These rights are exercisable beginning in 2022 and are accelerated in certain events. The redeemable noncontrolling interest is measured at the greater of the amount that would be paid if settlement occurred as of the balance sheet date based on the contractually defined redemption value ($18.7 million as of March 27, 2021) and the carrying amount adjusted for net income (loss) attributable to the noncontrolling interest. As the noncontrolling interest holders have the ability to require the Company to purchase the remaining 8% interest, the noncontrolling interest is classified in the mezzanine section of the unaudited condensed consolidated balance sheets, which is presented above the equity section and below liabilities. The amount that the Company could be required to pay to purchase the remaining 8% equity interest is not limited. As part of the Citoxlab acquisition in 2019, the Company acquired an approximate 90% equity interest in a subsidiary that was fully consolidated under the voting interest model, which included an approximate 10% redeemable noncontrolling interest. In February 2020, the Company purchased the remaining approximate 10% noncontrolling interest for approximately $4 million and assumption of a contingent consideration liability payable to the former shareholders. See Note 7. “Fair Value”. In 2019, the Company acquired an 80% equity interest that is fully consolidated under the voting interest model, which includes a 20% redeemable noncontrolling interest. The Company has the right to purchase, and the noncontrolling interest holders have the right to sell, the remaining 20% equity interest at its appraised value. These rights are exercisable beginning in 2022. The redeemable noncontrolling interest is measured at the greater of the amount that would be paid if settlement occurred as of the balance sheet date based on the appraised value and the carrying amount adjusted for net income (loss) attributable to the noncontrolling interest or a predetermined floor value. As the noncontrolling interest holders have the ability to require the Company to purchase the remaining 20% interest, the noncontrolling interest is classified in the mezzanine section of the unaudited condensed consolidated balance sheets, which is presented above the equity section and below liabilities. The amount that the Company could be required to pay to purchase the remaining 20% equity interest is not limited. The following table provides a rollforward of the activity related to the Company’s redeemable noncontrolling interests: Three Months Ended March 27, 2021 March 28, 2020 (in thousands) Beginning balance $ 25,499 $ 28,647 Adjustment to Vital River redemption value 835 — Purchase of a 10% redeemable noncontrolling interest — (3,732) Net income (loss) attributable to noncontrolling interests 1,716 (332) Foreign currency translation (15) (544) Ending balance $ 28,035 $ 24,039

INCOME TAXES

INCOME TAXES	3 Months Ended
	Mar. 27, 2021
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES The Company’s effective tax rates for the three months ended March 27, 2021 and March 28, 2020 were 3.6% and 8.3%, respectively. For the three months ended March 27, 2021, the decrease was primarily attributable to increased tax benefit from stock-based compensation deductions in the first quarter of 2021 compared to the corresponding period in 2020. For the three months ended March 27, 2021, the Company’s unrecognized tax benefits increased by $0.3 million to $25.3 million, primarily due to an additional quarter of Canadian Scientific Research and Experimental Development Credit Reserves, state tax positions, and unfavorable foreign exchange, partially offset by decreases due to dispositions. The accrued interest on unrecognized tax benefits was $2.4 million at March 27, 2021 . The Company estimates that it is reasonably possible that the unrecognized tax benefits will decrease by approximately $1.0 million over the next twelve-month period, primarily due to expiring statutes of limitations. The Company conducts business in a number of tax jurisdictions. As a result, it is subject to tax audits on a regular basis including, but not limited to, such major jurisdictions as the U.S., the U.K., China, France, Germany, and Canada. With few exceptions, the Company is no longer subject to U.S. and international income tax examinations for years before 2017. The Company and certain of its subsidiaries have ongoing tax controversies in the U.S., France, China, Germany, India, and Canada. The Company does not anticipate resolution of these audits will have a material impact on its consolidated financial statements.

PENSION AND OTHER POST-RETIREME

PENSION AND OTHER POST-RETIREMENT BENEFIT PLANS	3 Months Ended
	Mar. 27, 2021
Retirement Benefits [Abstract]
PENSION AND OTHER POST-RETIREMENT BENEFIT PLANS	PENSION AND OTHER POST-RETIREMENT BENEFIT PLANS The following table provides the components of net periodic cost for the Company’s pension, deferred compensation and executive supplemental life insurance retirement plans: Three Months Ended March 27, 2021 March 28, 2020 (in thousands) Service cost $ 911 $ 797 Interest cost 1,344 2,355 Expected return on plan assets (1,983) (2,981) Amortization of prior service cost (credit) (128) (125) Amortization of net loss 1,110 1,586 Other adjustments — 125 Net periodic cost $ 1,254 $ 1,757 Service cost is recorded as an operating expense within the accompanying unaudited condensed consolidated statements of income. All other components of net periodic costs are recorded in Other expense, net in the accompanying unaudited condensed consolidated statements of income. The net periodic cost for the Company’s other post-retirement benefit plan for the three months ended March 27, 2021 and March 28, 2020 was not significant.

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	3 Months Ended
	Mar. 27, 2021
Share-based Payment Arrangement [Abstract]
STOCK-BASED COMPENSATION	STOCK-BASED COMPENSATION The Company has stock-based compensation plans under which employees and non-employee directors may be granted stock-based awards such as stock options, restricted stock, RSUs, and PSUs. The following table provides stock-based compensation by the financial statement line item in which it is reflected: Three Months Ended March 27, 2021 March 28, 2020 (in thousands) Cost of revenue $ 2,713 $ 2,035 Selling, general and administrative 10,476 8,925 Stock-based compensation, before income taxes 13,189 10,960 Provision for income taxes (1,987) (1,551) Stock-based compensation, net of income taxes $ 11,202 $ 9,409

FOREIGN CURRENCY CONTRACTS

FOREIGN CURRENCY CONTRACTS	3 Months Ended
	Mar. 27, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
FOREIGN CURRENCY CONTRACTS	FOREIGN CURRENCY CONTRACTS Cross currency loans The Company periodically enters into foreign exchange forward contracts to limit its foreign currency exposure related to U.S. dollar denominated loans borrowed by a non-U.S. Euro functional currency entity under the Company’s Credit Facility. These contracts are not designated as hedging instruments. Any gains or losses on these forward contracts are recognized immediately within Interest expense in the unaudited condensed consolidated statements of income. The Company had no open forward contracts related to a U.S. dollar denominated loan borrowed by a non-U.S. Euro functional currency a t March 27, 2021 or December 26, 2020. The following table summarizes the effect of the foreign exchange forward contracts entered into to limit the Company’s foreign currency exposure related to U.S. dollar denominated loans borrowed by a non-U.S. Euro functional currency entity under the Credit Facility on the Company’s unaudited condensed consolidated statements of income: March 27, 2021 March 28, 2020 Location of gain (loss) Financial statement caption amount Amount of gain (loss) Financial statement caption amount Amount of gain (loss) (in thousands) Three Months Ended: Interest expense $ (29,719) $ 13,977 $ (15,067) $ 6,067 Intercompany loans The Company periodically enters into foreign exchange forward contracts to limit its foreign currency exposure related to certain intercompany loans. These contracts are not designated as hedging instruments. Any gains or losses on forward contracts associated with intercompany loans are recognized immediately in Other income (expense), net and are largely offset by the remeasurement of the underlying intercompany loans. The Company did not enter into foreign currency forward contracts related to certain intercompany loans during 2021 and 2020. The Company settled one foreign currency forward contract related to certain intercompany loans in 2020, and recognized an immaterial loss during the three months ended March 28, 2020 recognized in Other expense, net.

RESTRUCTURING AND ASSET IMPAIRM

RESTRUCTURING AND ASSET IMPAIRMENTS	3 Months Ended
	Mar. 27, 2021
Restructuring and Related Activities [Abstract]
RESTRUCTURING AND ASSET IMPAIRMENTS	RESTRUCTURING AND ASSET IMPAIRMENTS Global Restructuring Initiatives In recent fiscal years, the Company has undertaken productivity improvement initiatives within all reportable segments at various locations across the U.S., Canada, Europe, and China. This includes workforce right-sizing and scalability initiatives, resulting in severance and transition costs; and cost related to the consolidation of facilities, resulting in asset impairment and accelerated depreciation charges. The following table presents a summary of restructuring costs related to these initiatives within the unaudited condensed consolidated statements of income. Three Months Ended March 27, 2021 March 28, 2020 Severance and Transition Costs Asset Impairments and Other Costs Total Severance and Transition Costs Asset Impairments and Other Costs Total (in thousands) Cost of services provided and products sold (excluding amortization of intangible assets) $ 523 $ 40 $ 563 $ 247 $ 229 $ 476 Selling, general and administrative 39 147 186 83 — 83 Total $ 562 $ 187 $ 749 $ 330 $ 229 $ 559 The following table presents restructuring costs by reportable segment for these productivity improvement initiatives: Three Months Ended March 27, 2021 March 28, 2020 (in thousands) RMS $ 7 $ 220 DSA 559 83 Manufacturing 334 256 Unallocated corporate (151) — Total $ 749 $ 559 Rollforward of restructuring activities The following table provides a rollforward for all of the Company’s severance and transition costs and certain lease related costs related to all restructuring activities: Three Months Ended March 27, 2021 March 28, 2020 (in thousands) Beginning balance $ 5,816 $ 6,406 Expense (excluding non-cash charges) 749 517 Payments / utilization (2,465) (4,243) Other non-cash adjustments (1,831) — Foreign currency adjustments (48) (149) Ending balance $ 2,221 $ 2,531

LEASES

LEASES	3 Months Ended
	Mar. 27, 2021
Leases [Abstract]
LEASES	LEASES Operating and Finance Leases Right-of-use lease assets and lease liabilities are reported in the Company’s unaudited condensed consolidated balance sheets as follows: March 27, 2021 December 26, 2020 (in thousands) Operating leases Operating lease right-of-use assets, net $ 197,668 $ 178,220 Other current liabilities $ 25,868 $ 24,674 Operating lease right-of-use liabilities 173,015 155,595 Total operating lease liabilities $ 198,883 $ 180,269 Finance leases Property, plant and equipment, net $ 31,437 $ 31,614 Current portion of long-term debt and finance leases $ 2,823 $ 3,018 Long-term debt, net and finance leases 26,021 26,029 Total finance lease liabilities $ 28,844 $ 29,047 The components of operating and finance lease costs were as follows: Three Months Ended March 27, 2021 March 28, 2020 (in thousands) Operating lease costs $ 9,352 $ 8,077 Finance lease costs: Amortization of right-of-use assets 848 951 Interest on lease liabilities 328 340 Short-term lease costs 950 589 Variable lease costs 883 1,045 Sublease income (374) (586) Total lease costs $ 11,987 $ 10,416 Other information related to leases was as follows: Supplemental cash flow information Three Months Ended March 27, 2021 March 28, 2020 (in thousands) Cash flows included in the measurement of lease liabilities: Operating cash flows from operating leases $ 8,503 $ 6,974 Operating cash flows from finance leases 328 340 Finance cash flows from finance leases 942 1,572 Non-cash leases activity: Right-of-use lease assets obtained in exchange for new operating lease liabilities $ 25,968 $ 25,407 Right-of-use lease assets obtained in exchange for new finance lease liabilities 86 593 Lease term and discount rate As of As of March 27, 2021 March 28, 2020 Weighted-average remaining lease term (in years) Operating lease 8.7 8.4 Finance lease 12.4 12.7 Weighted-average discount rate Operating lease 3.9 % 4.2 % Finance lease 4.5 % 4.5 % At the lease commencement date, the discount rate implicit in the lease is used to discount the lease liability if readily determinable. If not readily determinable or leases do not contain an implicit rate, the Company’s incremental borrowing rate is used as the discount rate, which is based on the information available at the lease commencement date and represents a rate that would be incurred to borrow, on a collateralized basis, over a similar term, an amount equal to the lease payments in a similar economic environment. As of March 27, 2021, maturities of operating and finance lease liabilities for each of the following five years and a total thereafter were as follows: Operating Leases Finance Leases (in thousands) 2021 (excluding the three months ended March 27, 2021) $ 24,996 $ 3,078 2022 30,659 3,738 2023 28,248 3,411 2024 27,113 3,181 2025 24,635 2,902 Thereafter 101,665 21,597 Total minimum future lease payments 237,316 37,907 Less: Imputed interest 38,433 9,063 Total lease liabilities $ 198,883 $ 28,844 Total minimum future lease payments (predominantly operating leases) of approximately $108 million for leases that have not commenced as of March 27, 2021, as the Company does not yet control the underlying assets, are not included in the unaudited condensed consolidated financial statements. These leases are expected to commence between fiscal years 2021 and 2024 with lease terms of approximately 8 to 15 years.
LEASES	LEASES Operating and Finance Leases Right-of-use lease assets and lease liabilities are reported in the Company’s unaudited condensed consolidated balance sheets as follows: March 27, 2021 December 26, 2020 (in thousands) Operating leases Operating lease right-of-use assets, net $ 197,668 $ 178,220 Other current liabilities $ 25,868 $ 24,674 Operating lease right-of-use liabilities 173,015 155,595 Total operating lease liabilities $ 198,883 $ 180,269 Finance leases Property, plant and equipment, net $ 31,437 $ 31,614 Current portion of long-term debt and finance leases $ 2,823 $ 3,018 Long-term debt, net and finance leases 26,021 26,029 Total finance lease liabilities $ 28,844 $ 29,047 The components of operating and finance lease costs were as follows: Three Months Ended March 27, 2021 March 28, 2020 (in thousands) Operating lease costs $ 9,352 $ 8,077 Finance lease costs: Amortization of right-of-use assets 848 951 Interest on lease liabilities 328 340 Short-term lease costs 950 589 Variable lease costs 883 1,045 Sublease income (374) (586) Total lease costs $ 11,987 $ 10,416 Other information related to leases was as follows: Supplemental cash flow information Three Months Ended March 27, 2021 March 28, 2020 (in thousands) Cash flows included in the measurement of lease liabilities: Operating cash flows from operating leases $ 8,503 $ 6,974 Operating cash flows from finance leases 328 340 Finance cash flows from finance leases 942 1,572 Non-cash leases activity: Right-of-use lease assets obtained in exchange for new operating lease liabilities $ 25,968 $ 25,407 Right-of-use lease assets obtained in exchange for new finance lease liabilities 86 593 Lease term and discount rate As of As of March 27, 2021 March 28, 2020 Weighted-average remaining lease term (in years) Operating lease 8.7 8.4 Finance lease 12.4 12.7 Weighted-average discount rate Operating lease 3.9 % 4.2 % Finance lease 4.5 % 4.5 % At the lease commencement date, the discount rate implicit in the lease is used to discount the lease liability if readily determinable. If not readily determinable or leases do not contain an implicit rate, the Company’s incremental borrowing rate is used as the discount rate, which is based on the information available at the lease commencement date and represents a rate that would be incurred to borrow, on a collateralized basis, over a similar term, an amount equal to the lease payments in a similar economic environment. As of March 27, 2021, maturities of operating and finance lease liabilities for each of the following five years and a total thereafter were as follows: Operating Leases Finance Leases (in thousands) 2021 (excluding the three months ended March 27, 2021) $ 24,996 $ 3,078 2022 30,659 3,738 2023 28,248 3,411 2024 27,113 3,181 2025 24,635 2,902 Thereafter 101,665 21,597 Total minimum future lease payments 237,316 37,907 Less: Imputed interest 38,433 9,063 Total lease liabilities $ 198,883 $ 28,844 Total minimum future lease payments (predominantly operating leases) of approximately $108 million for leases that have not commenced as of March 27, 2021, as the Company does not yet control the underlying assets, are not included in the unaudited condensed consolidated financial statements. These leases are expected to commence between fiscal years 2021 and 2024 with lease terms of approximately 8 to 15 years.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	3 Months Ended
	Mar. 27, 2021
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Litigation Various lawsuits, claims and proceedings of a nature considered normal to its business are pending against the Company. While the outcome of any of these proceedings cannot be accurately predicted, the Company does not believe the ultimate resolution of any of these existing matters would have a material adverse effect on the Company’s business or financial condition.

BASIS OF PRESENTATION (Policies

BASIS OF PRESENTATION (Policies)	3 Months Ended
	Mar. 27, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	The accompanying condensed consolidated financial statements are unaudited and have been prepared by Charles River Laboratories International, Inc. (the Company) in accordance with accounting principles generally accepted in the United States (U.S. GAAP) and pursuant to the rules and regulations of the Securities and Exchange Commission (SEC). The year-end condensed consolidated balance sheet data was derived from the Company’s audited consolidated financial statements, but does not include all disclosures required by U.S. GAAP. These unaudited condensed consolidated financial statements should be read in conjunction with the Company’s Annual Report on Form 10-K for fiscal year 2020. The unaudited condensed consolidated financial statements, in the opinion of management, reflect all normal and recurring adjustments necessary for a fair statement of the Company’s financial position and results of operations.
Use of Estimates	The preparation of unaudited condensed consolidated financial statements in accordance with U.S. GAAP requires that the Company make estimates and judgments that may affect the reported amounts of assets, liabilities, revenues, expenses and related disclosure of contingent assets and liabilities. On an on-going basis, the Company evaluates its estimates, judgments, and methodologies. The Company bases its estimates on historical experience and on various other assumptions that are believed to be reasonable, the results of which form the basis for making judgments about the carrying values of assets and liabilities. Actual results may differ from these estimates under different assumptions or conditions. Changes in estimates are reflected in reported results in the period in which they become known. On March 11, 2020, the World Health Organization declared the outbreak of a strain of novel coronavirus disease, COVID-19, a global pandemic. The COVID-19 pandemic is dynamic, and its ultimate scope, duration and effects are uncertain. This pandemic has and continues to result in, and any future epidemic or pandemic crises may potentially result in, direct and indirect adverse effects on the Company’s industry and customers, which in turn has (with respect to COVID-19) and may (with respect to future epidemics or crises) impact the Company’s business, results of operations and financial condition. Further, the COVID-19 pandemic may also affect the Company’s operating and financial results in a manner that is not presently known to the Company or that the Company currently does not expect to present significant risks to its operations or financial results. As of the date of issuance of these unaudited condensed consolidated financial statements, the Company is not aware of any specific event or circumstance that would require the Company to update estimates, judgments or revise the carrying value of any assets or liabilities. These estimates may change, as new events occur and additional information is obtained, and are recognized in the condensed consolidated financial statements as soon as they become known. Actual results could differ from those estimates and any such differences may be material to the Company’s condensed consolidated financial statements.
Consolidation	The Company’s unaudited condensed consolidated financial statements reflect its financial statements and those of its subsidiaries in which the Company holds a controlling financial interest. For consolidated entities in which the Company owns or is exposed to less than 100% of the economics, the Company records net income (loss) attributable to noncontrolling interests in its consolidated statements of income equal to the percentage of the economic or ownership interest retained in such entities by the respective noncontrolling parties. Intercompany balances and transactions are eliminated in consolidation.
Fiscal Period	The Company’s fiscal year is typically based on 52-weeks, with each quarter composed of 13 weeks ending on the last Saturday on, or closest to, March 31, June 30, September 30, and December 31.
Segment Reporting	The Company reports its results in three reportable segments: Research Models and Services (RMS), Discovery and Safety Assessment (DSA), and Manufacturing Support (Manufacturing). The Company’s RMS reportable segment includes the Research Models, Research Model Services, and Research Products businesses. Research Models includes the commercial production and sale of small research models, as well as the supply of large research models. Research Model Services includes: Genetically Engineered Models and Services (GEMS), which performs contract breeding and other services associated with genetically engineered models; Research Animal Diagnostic Services (RADS), which provides health monitoring and diagnostics services related to research models; and Insourcing Solutions (IS), which provides colony management of its clients’ research operations (including recruitment, training, staffing, and management services). Research Products supplies controlled, consistent, customized primary cells and blood components derived from normal and mobilized peripheral blood, bone marrow, and cord blood. The Company’s DSA reportable segment includes services required to take a drug through the early development process including discovery services, which are non-regulated services to assist clients with the identification, screening, and selection of a lead compound for drug development, and regulated and non-regulated (GLP and non-GLP) safety assessment services. The Company’s Manufacturing reportable segment includes Microbial Solutions, which provides in vitro (non-animal) lot-release testing products, microbial detection products, and species identification
Newly Adopted and Newly Issued Accounting Pronouncements	In January 2020, the Financial Accounting Standards Board (FASB) issue d ASU 2020-01, “Investments-Equity Securities (Topic 321), Investments-Equity Method and Joint Ventures (Topic 323), and Derivatives and Hedging (Topic 815).” ASU 2020-01 states any equity security transitioning from the alternative method of accounting under Topic 321 to the equity method, or vice versa, due to an observable transaction will be remeasured immediately before the transition. In addition, the ASU clarifies the accounting for certain non-derivative forward contracts or pur chased call options to acquire equity securities stating such instruments will be measured using the fair value principles of Topic 321 before settlement or exercise. This standard became effective for the Company in the three months ended March 27, 2021 and did not have a significant impact on the unaudited condensed consolidated financial statements and related disclosures. In December 2019, the FASB issued ASU 2019-12, “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes.” ASU 2019-12 simplifies the accounting for income taxes by removing exceptions within the general principles of Topic 740 regarding the calculation of deferred tax liabilities, the incremental approach for intraperiod tax allocation, and calculating income taxes in an interim period. In addition, the ASU adds clarifications to the accounting for franchise tax (or similar tax), which is partially based on income, evaluating tax basis of goodwill recognized from a business combination, and reflecting the effect of any enacted changes in tax laws or rates in the annual effective tax rate computation in the interim period that includes the enactment date. This standard became effective for the Company in the three months ended March 27, 2021 and did not have a significant impact on the unaudited condensed consolidated financial statements and related disclosures. Newly Issued Accounting Pronouncements In March 2020, the FASB issued ASU 2020-04, “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting.” The ASU , including subsequently issued updates, offers temp orary optional expedients and exceptions for applying U.S. GAAP to modifications to agreements such as loans, debt securities, derivatives, and borrowings which reference LIBOR or another reference rate that will partially discontinue after December 31, 2021 and fully cease by June 30, 2023. The expedients and exceptions provided by the standard do not apply to modifications made and hedging relationships entered into or evaluated after that, except for hedging relationships existing as of the phase-out date that an entity has elected certain optional expedients for and are retained through the end of the hedging relationship. The ASU is effective until the replacement for LIBOR is completed. The interest rate on the Company’s revolving credit facility, which was amended and restated in April 2021 (see Note 9. Long-term debt and finance lease obligations) matures in fiscal year 2026, is linked to LIBOR and alternative interest rates when LIBOR is discontinued. The Company is currently evaluating the impact this new standard will have on the consolidated financial statements and related disclosures, but does not believe there will be a material impact upon adoption.

BUSINESS COMBINATIONS (Tables)

BUSINESS COMBINATIONS (Tables)	3 Months Ended
	Mar. 27, 2021
Business Combinations [Abstract]
Schedule of Purchase Price Allocation	The preliminary purchase price allocation of $97.0 million, net of $0.8 million of cash acquired was as follows: December 31, 2020 (in thousands) Trade receivables $ 2,722 Other current assets (excluding cash) 221 Property, plant and equipment 2,382 Goodwill 71,585 Definite-lived intangible assets 24,540 Other long-term assets 2,055 Current liabilities (2,823) Deferred tax liabilities (2,529) Other long-term liabilities (1,123) Total purchase price allocation $ 97,030 August 6, 2020 (in thousands) Trade receivables $ 1,500 Inventories 551 Other current assets (excluding cash) 182 Property, plant and equipment 1,648 Goodwill 19,457 Definite-lived intangible assets 16,230 Other long-term assets 849 Current liabilities (1,360) Deferred tax liabilities (1,467) Other long-term liabilities (740) Total purchase price allocation $ 36,850 The purchase price allocation of $376.7 million, net of $3.1 million of cash acquired was as follows: January 3, 2020 (in thousands) Trade receivables $ 6,451 Inventories 8,468 Other current assets (excluding cash) 3,494 Property, plant and equipment 10,033 Goodwill 210,196 Definite-lived intangible assets 183,540 Other long-term assets 5,920 Current liabilities (5,188) Deferred tax liabilities (38,529) Other long-term liabilities (7,664) Total purchase price allocation $ 376,721
Schedule of Definite-Lived Intangible Assets Acquired as Part of Business Combination	The breakout of definite-lived intangible assets acquired was as follows: Definite-Lived Intangible Assets Weighted Average Amortization Life (in thousands) (in years) Client relationships $ 16,080 9 Developed technology 3,940 5 Other intangible assets 4,520 4 Total definite-lived intangible assets $ 24,540 7 The breakout of definite-lived intangible assets acquired was as follows: Definite-Lived Intangible Assets Weighted Average Amortization Life (in thousands) (in years) Client relationships $ 14,740 13 Other intangible assets 1,490 3 Total definite-lived intangible assets $ 16,230 12 The breakout of definite-lived intangible assets acquired was as follows: Definite-Lived Intangible Assets Weighted Average Amortization Life (in thousands) (in years) Client relationships $ 170,390 19 Trade name 7,330 10 Other intangible assets 5,820 3 Total definite-lived intangible assets $ 183,540 18
Schedule of Business Acquisition, Pro Forma Information	Three Months Ended March 28, 2020 (in thousands) (unaudited) Revenue $ 707,077 Net income attributable to common shareholders 55,705

REVENUE FROM CONTRACTS WITH C_2

REVENUE FROM CONTRACTS WITH CUSTOMERS (Tables)	3 Months Ended
	Mar. 27, 2021
Revenue from Contract with Customer [Abstract]
Schedule of Disaggregation of Revenue	The following table disaggregates the Company’s revenue by major business line and timing of transfer of products or services: Three Months Ended March 27, 2021 March 28, 2020 (in thousands) Timing of Revenue Recognition: RMS Services and products transferred over time $ 64,896 $ 60,041 Services and products transferred at a point in time 112,014 85,955 Total RMS revenue 176,910 145,996 DSA Services and products transferred over time 500,468 438,564 Services and products transferred at a point in time 710 119 Total DSA revenue 501,178 438,683 Manufacturing Services and products transferred over time 50,568 37,314 Services and products transferred at a point in time 95,910 85,066 Total Manufacturing revenue 146,478 122,380 Total revenue $ 824,566 $ 707,059 Revenue for each significant product or service offering is as follows: Three Months Ended March 27, 2021 March 28, 2020 (in thousands) RMS $ 176,910 $ 145,996 DSA 501,178 438,683 Manufacturing 146,478 122,380 Total revenue $ 824,566 $ 707,059 Revenue by geographic area is as follows: U.S. Europe Canada Asia Pacific Other Consolidated (in thousands) Three Months Ended: March 27, 2021 $ 448,482 $ 237,535 $ 77,107 $ 59,446 $ 1,996 $ 824,566 March 28, 2020 406,712 190,262 76,633 31,829 1,623 707,059
Schedule of Estimated Revenue Related to Performance Obligations	The following table inclu des estimated revenue expected to be recognized in the future related to performance obligations that are unsatisfied (or partially satisfied) as of March 27, 2021: Revenue Expected to be Recognized in Future Periods Less than 1 Year 1 to 3 Years 4 to 5 Years Beyond 5 Years Total (in thousands) DSA $ 212,919 $ 120,893 $ 4,404 $ 122 $ 338,338 Manufacturing 8,724 3,170 — — 11,894 Total $ 221,643 $ 124,063 $ 4,404 $ 122 $ 350,232
Schedule of Client Receivables, Contract Assets and Contract Liabilities	The following table provides information about client receivables, contract assets, and contract liabilities from contracts with customers: March 27, 2021 December 26, 2020 (in thousands) Balances from contracts with customers: Client receivables $ 463,800 $ 489,042 Contract assets (unbilled revenue) 154,044 135,400 Contract liabilities (current and long-term deferred revenue) 233,075 227,417 Contract liabilities (customer contract deposits) 36,652 42,244

SEGMENT INFORMATION (Tables)

SEGMENT INFORMATION (Tables)	3 Months Ended
	Mar. 27, 2021
Segment Reporting [Abstract]
Schedule of Revenue and Other Financial Information by Business Segment	The following table presents revenue and other financial information by reportable segment: Three Months Ended March 27, 2021 March 28, 2020 (in thousands) RMS Revenue $ 176,910 $ 145,996 Operating income 44,935 27,373 Depreciation and amortization 9,679 8,752 Capital expenditures 2,983 5,412 DSA Revenue $ 501,178 $ 438,683 Operating income 90,949 72,283 Depreciation and amortization 44,608 41,330 Capital expenditures 17,040 14,729 Manufacturing Revenue $ 146,478 $ 122,380 Operating income 49,437 41,112 Depreciation and amortization 6,569 6,366 Capital expenditures 7,110 5,161
Reconciliation of Segment Operating Income to Consolidated Operating Income	Reconciliations of segment operating income, depreciation and amortization, and capital expenditures to the respective consolidated amounts are as follows: Operating Income Depreciation and Amortization Capital Expenditures March 27, 2021 March 28, 2020 March 27, 2021 March 28, 2020 March 27, 2021 March 28, 2020 (in thousands) Three Months Ended: Total reportable segments $ 185,321 $ 140,768 $ 60,856 $ 56,448 $ 27,133 $ 25,302 Unallocated corporate (61,618) (46,487) 652 812 897 419 Total consolidated $ 123,703 $ 94,281 $ 61,508 $ 57,260 $ 28,030 $ 25,721
Revenue Disaggregated by Products and Services and Geographic Area	The following table disaggregates the Company’s revenue by major business line and timing of transfer of products or services: Three Months Ended March 27, 2021 March 28, 2020 (in thousands) Timing of Revenue Recognition: RMS Services and products transferred over time $ 64,896 $ 60,041 Services and products transferred at a point in time 112,014 85,955 Total RMS revenue 176,910 145,996 DSA Services and products transferred over time 500,468 438,564 Services and products transferred at a point in time 710 119 Total DSA revenue 501,178 438,683 Manufacturing Services and products transferred over time 50,568 37,314 Services and products transferred at a point in time 95,910 85,066 Total Manufacturing revenue 146,478 122,380 Total revenue $ 824,566 $ 707,059 Revenue for each significant product or service offering is as follows: Three Months Ended March 27, 2021 March 28, 2020 (in thousands) RMS $ 176,910 $ 145,996 DSA 501,178 438,683 Manufacturing 146,478 122,380 Total revenue $ 824,566 $ 707,059 Revenue by geographic area is as follows: U.S. Europe Canada Asia Pacific Other Consolidated (in thousands) Three Months Ended: March 27, 2021 $ 448,482 $ 237,535 $ 77,107 $ 59,446 $ 1,996 $ 824,566 March 28, 2020 406,712 190,262 76,633 31,829 1,623 707,059
Summary of Unallocated Corporate Overhead	A summary of unallocated corporate expense consists of the following: Three Months Ended March 27, 2021 March 28, 2020 (in thousands) Stock-based compensation $ 7,642 $ 6,704 Compensation, benefits, and other employee-related expenses 27,362 21,980 External consulting and other service expenses 7,356 2,469 Information technology 4,095 3,716 Depreciation 652 812 Acquisition and integration 10,560 6,983 Other general unallocated corporate 3,951 3,823 Total unallocated corporate expense $ 61,618 $ 46,487

SUPPLEMENTAL BALANCE SHEET IN_2

SUPPLEMENTAL BALANCE SHEET INFORMATION (Tables)	3 Months Ended
	Mar. 27, 2021
Supplemental Balance Sheet Information [Abstract]
Composition of Net Trade Receivables	The composition of trade receivables, net is as follows: March 27, 2021 December 26, 2020 (in thousands) Client receivables $ 463,800 $ 489,042 Unbilled revenue 154,044 135,400 Total 617,844 624,442 Less: Allowance for doubtful accounts (7,278) (6,702) Trade receivables, net $ 610,566 $ 617,740
Composition of Inventories	The composition of inventories is as follows: March 27, 2021 December 26, 2020 (in thousands) Raw materials and supplies $ 26,726 $ 28,317 Work in process 32,619 36,755 Finished products 134,239 120,623 Inventories $ 193,584 $ 185,695
Composition of Other Current Assets	The composition of other current assets is as follows: March 27, 2021 December 26, 2020 (in thousands) Prepaid income tax $ 66,885 $ 68,462 Short-term investments 1,025 1,024 Restricted cash 4,012 3,074 Other current assets $ 71,922 $ 72,560
Composition of Other Assets	The composition of other assets is as follows: March 27, 2021 December 26, 2020 (in thousands) Venture capital investments $ 175,506 $ 197,100 Strategic equity investments 35,772 24,704 Life insurance policies 46,258 43,827 Other long-term income tax assets 22,827 23,485 Restricted cash 1,602 1,621 Long-term pension assets 33,435 31,915 Other 34,031 29,974 Other assets $ 349,431 $ 352,626
Composition of Other Current Liabilities	The composition of other current liabilities is as follows: March 27, 2021 December 26, 2020 (in thousands) Current portion of operating lease right-of-use liabilities $ 25,868 $ 24,674 Accrued income taxes 24,952 24,884 Customer contract deposits 36,652 42,244 Other 9,875 10,675 Other current liabilities $ 97,347 $ 102,477
Composition of Other Long-Term Liabilities	The composition of other long-term liabilities is as follows: March 27, 2021 December 26, 2020 (in thousands) U.S. Transition Tax $ 48,781 $ 48,781 Long-term pension liability, accrued executive supplemental life insurance retirement plan and deferred compensation plan 74,223 74,233 Long-term deferred revenue 20,043 19,475 Other 63,961 62,726 Other long-term liabilities $ 207,008 $ 205,215

FAIR VALUE (Tables)

FAIR VALUE (Tables)	3 Months Ended
	Mar. 27, 2021
Fair Value Disclosures [Abstract]
Summary of Assets and Liabilities Measured at Fair Value on a Recurring Basis	Assets and liabilities measured at fair value on a recurring basis are summarized below: March 27, 2021 Level 1 Level 2 Level 3 Total (in thousands) Cash equivalents $ — $ 6,172 $ — $ 6,172 Other assets: Life insurance policies — 38,250 — 38,250 Total assets measured at fair value $ — $ 44,422 $ — $ 44,422 Other liabilities measured at fair value: Contingent consideration $ — $ — $ 33,163 $ 33,163 Total liabilities measured at fair value $ — $ — $ 33,163 $ 33,163 December 26, 2020 Level 1 Level 2 Level 3 Total (in thousands) Cash equivalents $ — $ 2,273 $ — $ 2,273 Other assets: Life insurance policies — 35,770 — 35,770 Total assets measured at fair value $ — $ 38,043 $ — $ 38,043 Other liabilities measured at fair value: Contingent consideration $ — $ — $ 2,328 $ 2,328 Total liabilities measured at fair value $ — $ — $ 2,328 $ 2,328 March 27, 2021 December 26, 2020 Book Value Fair Value Book Value Fair Value 5.5% Senior Notes due 2026 $ — $ — $ 500,000 $ 523,100 4.25% Senior Notes due 2028 500,000 513,750 500,000 523,750 3.75% Senior Notes due 2029 500,000 501,250 — — 4.0% Senior Notes due 2031 500,000 504,350 — —
Rollforward of Contingent Consideration Related to Previous Acquisitions	The following table provides a rollforward of the contingent consideration related to the Company’s business combinations. See Note 2, “Business Combinations.” Three Months Ended March 27, 2021 March 28, 2020 (in thousands) Beginning balance $ 2,328 $ 712 Additions 29,990 2,131 Fair value adjustments 917 — Payments — (218) Foreign currency (72) (62) Ending balance $ 33,163 $ 2,563

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS (Tables)	3 Months Ended
	Mar. 27, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	The following table provides a rollforward of the Company’s goodwill: Adjustments to Goodwill December 26, 2020 Acquisitions Foreign Exchange March 27, 2021 (in thousands) RMS $ 287,759 $ — $ (169) $ 287,590 DSA 1,378,130 88,611 (7,726) 1,459,015 Manufacturing 143,279 — 746 144,025 Goodwill $ 1,809,168 $ 88,611 $ (7,149) $ 1,890,630
Schedule of Intangible Assets	The following table displays intangible assets, net by major class: March 27, 2021 December 26, 2020 Gross Accumulated Amortization Net Gross Accumulated Amortization Net (in thousands) Backlog $ 610 $ (152) $ 458 $ 29,233 $ (29,233) $ — Technology 133,667 (85,610) 48,057 130,907 (81,305) 49,602 Trademarks and trade names 12,231 (2,112) 10,119 15,870 (5,648) 10,222 Other 28,736 (4,189) 24,547 20,903 (14,633) 6,270 Other intangible assets 175,244 (92,063) 83,181 196,913 (130,819) 66,094 Client relationships 1,152,499 (440,115) 712,384 1,137,331 (415,826) 721,505 Intangible assets $ 1,327,743 $ (532,178) $ 795,565 $ 1,334,244 $ (546,645) $ 787,599

LONG-TERM DEBT AND FINANCE LE_2

LONG-TERM DEBT AND FINANCE LEASE OBLIGATIONS (Tables)	3 Months Ended
	Mar. 27, 2021
Debt Disclosure [Abstract]
Schedule of Long-term Debt and Finance Lease Obligations	Long-term debt, net and finance leases consists of the following: March 27, 2021 December 26, 2020 (in thousands) Term loans $ — $ 146,875 Revolving facility 694,135 814,752 5.5% Senior Notes due 2026 — 500,000 4.25% Senior Notes due 2028 500,000 500,000 3.75% Senior Notes due 2029 500,000 — 4.0% Senior Notes due 2031 500,000 — Other debt 369 3,457 Finance leases (Note 16) 28,844 29,047 Total debt and finance leases 2,223,348 1,994,131 Less: Current portion of long-term debt 109 47,196 Current portion of finance leases (Note 16) 2,823 3,018 Current portion of long-term debt and finance leases 2,932 50,214 Long-term debt and finance leases 2,220,416 1,943,917 Debt discount and debt issuance costs (18,082) (14,346) Long-term debt, net and finance leases $ 2,202,334 $ 1,929,571
Schedule of Principal Maturities of Existing Debt	Principal maturities of existing debt, giving effect to the amended and restated Credit Agreement, for the periods set forth in the table below, are as follows: Principal (in thousands) 2021 (excluding the three months ended March 27, 2021) $ 109 2022 — 2023 — 2024 260 2025 — Thereafter 2,194,135 Total $ 2,194,504

EQUITY AND NONCONTROLLING INT_2

EQUITY AND NONCONTROLLING INTERESTS (Tables)	3 Months Ended
	Mar. 27, 2021
Equity [Abstract]
Reconciliation of the Numerator and Denominator in the Computations of the Basic and Diluted Earnings Per Share	The following table reconciles the numerator and denominator in the computations of basic and diluted earnings per share: Three Months Ended March 27, 2021 March 28, 2020 (in thousands) Numerator: Net income $ 63,935 $ 50,837 Less: Net income attributable to noncontrolling interests 2,405 68 Net income attributable to common shareholders $ 61,530 $ 50,769 Denominator: Weighted-average shares outstanding - Basic 49,980 49,189 Effect of dilutive securities: Stock options, restricted stock units and performance share units 1,095 777 Weighted-average shares outstanding - Diluted 51,075 49,966
Schedule of Accumulated Other Comprehensive Income (Loss)	Changes to each component of accumulated other comprehensive income (loss), net of income taxes, are as follows: Foreign Currency Translation Adjustment Pension and Other Post-Retirement Benefit Plans Total (in thousands) December 26, 2020 $ (73,884) $ (64,990) $ (138,874) Other comprehensive income before reclassifications 9,844 — 9,844 Amounts reclassified from accumulated other comprehensive income — 988 988 Net current period other comprehensive income 9,844 988 10,832 Income tax (benefit) expense (1,270) 245 (1,025) March 27, 2021 $ (62,770) $ (64,247) $ (127,017)
Rollforward Redeemable Noncontrolling Interest	The following table provides a rollforward of the activity related to the Company’s redeemable noncontrolling interests: Three Months Ended March 27, 2021 March 28, 2020 (in thousands) Beginning balance $ 25,499 $ 28,647 Adjustment to Vital River redemption value 835 — Purchase of a 10% redeemable noncontrolling interest — (3,732) Net income (loss) attributable to noncontrolling interests 1,716 (332) Foreign currency translation (15) (544) Ending balance $ 28,035 $ 24,039

PENSION AND OTHER POST-RETIRE_2

PENSION AND OTHER POST-RETIREMENT BENEFIT PLANS (Tables)	3 Months Ended
	Mar. 27, 2021
Retirement Benefits [Abstract]
Schedule of Net Periodic Cost	The following table provides the components of net periodic cost for the Company’s pension, deferred compensation and executive supplemental life insurance retirement plans: Three Months Ended March 27, 2021 March 28, 2020 (in thousands) Service cost $ 911 $ 797 Interest cost 1,344 2,355 Expected return on plan assets (1,983) (2,981) Amortization of prior service cost (credit) (128) (125) Amortization of net loss 1,110 1,586 Other adjustments — 125 Net periodic cost $ 1,254 $ 1,757

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	3 Months Ended
	Mar. 27, 2021
Share-based Payment Arrangement [Abstract]
Schedule of Stock-Based Compensation Expense	The following table provides stock-based compensation by the financial statement line item in which it is reflected: Three Months Ended March 27, 2021 March 28, 2020 (in thousands) Cost of revenue $ 2,713 $ 2,035 Selling, general and administrative 10,476 8,925 Stock-based compensation, before income taxes 13,189 10,960 Provision for income taxes (1,987) (1,551) Stock-based compensation, net of income taxes $ 11,202 $ 9,409

FOREIGN CURRENCY CONTRACTS (Tab

FOREIGN CURRENCY CONTRACTS (Tables)	3 Months Ended
	Mar. 27, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments on Statements of Income	The following table summarizes the effect of the foreign exchange forward contracts entered into to limit the Company’s foreign currency exposure related to U.S. dollar denominated loans borrowed by a non-U.S. Euro functional currency entity under the Credit Facility on the Company’s unaudited condensed consolidated statements of income: March 27, 2021 March 28, 2020 Location of gain (loss) Financial statement caption amount Amount of gain (loss) Financial statement caption amount Amount of gain (loss) (in thousands) Three Months Ended: Interest expense $ (29,719) $ 13,977 $ (15,067) $ 6,067

RESTRUCTURING AND ASSET IMPAI_2

RESTRUCTURING AND ASSET IMPAIRMENTS (Tables)	3 Months Ended
	Mar. 27, 2021
Restructuring and Related Activities [Abstract]
Schedule of Restructuring Costs	The following table presents a summary of restructuring costs related to these initiatives within the unaudited condensed consolidated statements of income. Three Months Ended March 27, 2021 March 28, 2020 Severance and Transition Costs Asset Impairments and Other Costs Total Severance and Transition Costs Asset Impairments and Other Costs Total (in thousands) Cost of services provided and products sold (excluding amortization of intangible assets) $ 523 $ 40 $ 563 $ 247 $ 229 $ 476 Selling, general and administrative 39 147 186 83 — 83 Total $ 562 $ 187 $ 749 $ 330 $ 229 $ 559 The following table presents restructuring costs by reportable segment for these productivity improvement initiatives: Three Months Ended March 27, 2021 March 28, 2020 (in thousands) RMS $ 7 $ 220 DSA 559 83 Manufacturing 334 256 Unallocated corporate (151) — Total $ 749 $ 559
Rollforward of Company's Severance and Transition Costs and Lease Obligation Liabilities	The following table provides a rollforward for all of the Company’s severance and transition costs and certain lease related costs related to all restructuring activities: Three Months Ended March 27, 2021 March 28, 2020 (in thousands) Beginning balance $ 5,816 $ 6,406 Expense (excluding non-cash charges) 749 517 Payments / utilization (2,465) (4,243) Other non-cash adjustments (1,831) — Foreign currency adjustments (48) (149) Ending balance $ 2,221 $ 2,531

LEASES (Tables)

LEASES (Tables)	3 Months Ended
	Mar. 27, 2021
Leases [Abstract]
Schedule of Right-of-Use Lease Assets and Lease Liabilities in Condensed Financial Statements	Right-of-use lease assets and lease liabilities are reported in the Company’s unaudited condensed consolidated balance sheets as follows: March 27, 2021 December 26, 2020 (in thousands) Operating leases Operating lease right-of-use assets, net $ 197,668 $ 178,220 Other current liabilities $ 25,868 $ 24,674 Operating lease right-of-use liabilities 173,015 155,595 Total operating lease liabilities $ 198,883 $ 180,269 Finance leases Property, plant and equipment, net $ 31,437 $ 31,614 Current portion of long-term debt and finance leases $ 2,823 $ 3,018 Long-term debt, net and finance leases 26,021 26,029 Total finance lease liabilities $ 28,844 $ 29,047
Schedule of Operating and Finance Lease Costs and Supplemental Cash Flow Information	The components of operating and finance lease costs were as follows: Three Months Ended March 27, 2021 March 28, 2020 (in thousands) Operating lease costs $ 9,352 $ 8,077 Finance lease costs: Amortization of right-of-use assets 848 951 Interest on lease liabilities 328 340 Short-term lease costs 950 589 Variable lease costs 883 1,045 Sublease income (374) (586) Total lease costs $ 11,987 $ 10,416 Supplemental cash flow information Three Months Ended March 27, 2021 March 28, 2020 (in thousands) Cash flows included in the measurement of lease liabilities: Operating cash flows from operating leases $ 8,503 $ 6,974 Operating cash flows from finance leases 328 340 Finance cash flows from finance leases 942 1,572 Non-cash leases activity: Right-of-use lease assets obtained in exchange for new operating lease liabilities $ 25,968 $ 25,407 Right-of-use lease assets obtained in exchange for new finance lease liabilities 86 593 Lease term and discount rate As of As of March 27, 2021 March 28, 2020 Weighted-average remaining lease term (in years) Operating lease 8.7 8.4 Finance lease 12.4 12.7 Weighted-average discount rate Operating lease 3.9 % 4.2 % Finance lease 4.5 % 4.5 %
Schedule of Future Minimum Lease Payments Under Non-Cancellable Operating Leases	As of March 27, 2021, maturities of operating and finance lease liabilities for each of the following five years and a total thereafter were as follows: Operating Leases Finance Leases (in thousands) 2021 (excluding the three months ended March 27, 2021) $ 24,996 $ 3,078 2022 30,659 3,738 2023 28,248 3,411 2024 27,113 3,181 2025 24,635 2,902 Thereafter 101,665 21,597 Total minimum future lease payments 237,316 37,907 Less: Imputed interest 38,433 9,063 Total lease liabilities $ 198,883 $ 28,844
Schedule of Future Minimum Lease Payments Under Non-Cancellable Finance Leases	As of March 27, 2021, maturities of operating and finance lease liabilities for each of the following five years and a total thereafter were as follows: Operating Leases Finance Leases (in thousands) 2021 (excluding the three months ended March 27, 2021) $ 24,996 $ 3,078 2022 30,659 3,738 2023 28,248 3,411 2024 27,113 3,181 2025 24,635 2,902 Thereafter 101,665 21,597 Total minimum future lease payments 237,316 37,907 Less: Imputed interest 38,433 9,063 Total lease liabilities $ 198,883 $ 28,844

BASIS OF PRESENTATION (Details)

BASIS OF PRESENTATION (Details)	3 Months Ended
	Mar. 27, 2021segment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of reportable segments	3

BUSINESS COMBINATIONS - Narrati

BUSINESS COMBINATIONS - Narrative (Details) $ in Thousands, £ in Millions	Mar. 30, 2021USD ($)	Mar. 30, 2021GBP (£)	Mar. 29, 2021USD ($)	Mar. 03, 2021USD ($)	Dec. 31, 2020USD ($)	Aug. 06, 2020USD ($)	Jan. 03, 2020USD ($)	Mar. 27, 2021USD ($)	Mar. 28, 2020USD ($)	Dec. 26, 2020USD ($)
Business Acquisition [Line Items]
Goodwill								$ 1,890,630		$ 1,809,168
Retrogenix Limited
Business Acquisition [Line Items]
Integration related costs and transaction costs								800
Retrogenix Limited | Subsequent Event
Business Acquisition [Line Items]
Purchase price	$ 48,000	£ 35
Consideration contingent upon future performance	$ 7,000	£ 5
Cognate BioServices, Inc.
Business Acquisition [Line Items]
Integration related costs and transaction costs								7,200
Cognate BioServices, Inc. | Subsequent Event
Business Acquisition [Line Items]
Purchase price			$ 875,000
Distributed Bio, Inc.
Business Acquisition [Line Items]
Purchase price					$ 97,000
Consideration contingent upon future performance					21,000
Contingent consideration liability					14,000
Purchase price allocation					97,030
Cash acquired					800
Integration related costs and transaction costs								700
Cash portion of consideration transferred					80,800
Payments to settle promissory note					3,000
Goodwill					$ 71,585
Weighted-average amortization life					7 years
Definite-lived intangible assets					$ 24,540
Property, plant and equipment					$ 2,382
Cellero, LLC
Business Acquisition [Line Items]
Purchase price						$ 37,400
Purchase price allocation						36,850
Cash acquired						500
Integration related costs and transaction costs								400
Goodwill, amount expected to be deductible for tax purposes						10,800
Goodwill						$ 19,457
Weighted-average amortization life						12 years
Definite-lived intangible assets						$ 16,230
Property, plant and equipment						$ 1,648
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								$ 100	$ 5,700
Goodwill							$ 210,196
Weighted-average amortization life							18 years
Definite-lived intangible assets							$ 183,540
Property, plant and equipment							$ 10,033
Other Acquisitions
Business Acquisition [Line Items]
Purchase price				$ 35,600
Contingent consideration liability				15,900
Cash portion of consideration transferred				19,700						$ 5,500
Goodwill				17,300
Definite-lived intangible assets				15,200
Property, plant and equipment				$ 3,000
Other Acquisitions | Supplier relationships
Business Acquisition [Line Items]
Weighted-average amortization life				4 years
Other Acquisitions | Maximum
Business Acquisition [Line Items]
Contingent consideration liability				$ 17,500
Depreciation and Amortization Expense | HemaCare Corporation
Business Acquisition [Line Items]
Adjustments related to prior period									$ 200

BUSINESS COMBINATIONS - Purchas

BUSINESS COMBINATIONS - Purchase Price Allocation (Details) - USD ($) $ in Thousands	Mar. 27, 2021	Dec. 31, 2020	Dec. 26, 2020	Aug. 06, 2020	Jan. 03, 2020
Business Acquisition [Line Items]
Goodwill	$ 1,890,630		$ 1,809,168
Distributed Bio, Inc.
Business Acquisition [Line Items]
Trade receivables		$ 2,722
Other current assets (excluding cash)		221
Property, plant and equipment		2,382
Goodwill		71,585
Definite-lived intangible assets		24,540
Other long-term assets		2,055
Current liabilities		(2,823)
Deferred tax liabilities		(2,529)
Other long-term liabilities		(1,123)
Total purchase price allocation		$ 97,030
Cellero, LLC
Business Acquisition [Line Items]
Trade receivables				$ 1,500
Inventories				551
Other current assets (excluding cash)				182
Property, plant and equipment				1,648
Goodwill				19,457
Definite-lived intangible assets				16,230
Other long-term assets				849
Current liabilities				(1,360)
Deferred tax liabilities				(1,467)
Other long-term liabilities				(740)
Total purchase price allocation				$ 36,850
HemaCare Corporation
Business Acquisition [Line Items]
Trade receivables					$ 6,451
Inventories					8,468
Other current assets (excluding cash)					3,494
Property, plant and equipment					10,033
Goodwill					210,196
Definite-lived intangible assets					183,540
Other long-term assets					5,920
Current liabilities					(5,188)
Deferred tax liabilities					(38,529)
Other long-term liabilities					(7,664)
Total purchase price allocation					$ 376,721

BUSINESS COMBINATIONS - Definit

BUSINESS COMBINATIONS - Definite-Lived Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Aug. 06, 2020	Jan. 03, 2020
Distributed Bio, Inc.
Business Acquisition [Line Items]
Definite-lived intangible assets acquired	$ 24,540
Weighted-average amortization life	7 years
Cellero, LLC
Business Acquisition [Line Items]
Definite-lived intangible assets acquired		$ 16,230
Weighted-average amortization life		12 years
HemaCare Corporation
Business Acquisition [Line Items]
Definite-lived intangible assets acquired			$ 183,540
Weighted-average amortization life			18 years
Customer and client relationships | Distributed Bio, Inc.
Business Acquisition [Line Items]
Definite-lived intangible assets acquired	$ 16,080
Weighted-average amortization life	9 years
Customer and client relationships | Cellero, LLC
Business Acquisition [Line Items]
Definite-lived intangible assets acquired		$ 14,740
Weighted-average amortization life		13 years
Customer and client relationships | HemaCare Corporation
Business Acquisition [Line Items]
Definite-lived intangible assets acquired			$ 170,390
Weighted-average amortization life			19 years
Developed technology | Distributed Bio, Inc.
Business Acquisition [Line Items]
Definite-lived intangible assets acquired	$ 3,940
Weighted-average amortization life	5 years
Trade name | HemaCare Corporation
Business Acquisition [Line Items]
Definite-lived intangible assets acquired			$ 7,330
Weighted-average amortization life			10 years
Other intangible assets | Distributed Bio, Inc.
Business Acquisition [Line Items]
Definite-lived intangible assets acquired	$ 4,520
Weighted-average amortization life	4 years
Other intangible assets | Cellero, LLC
Business Acquisition [Line Items]
Definite-lived intangible assets acquired		$ 1,490
Weighted-average amortization life		3 years
Other intangible assets | HemaCare Corporation
Business Acquisition [Line Items]
Definite-lived intangible assets acquired			$ 5,820
Weighted-average amortization life			3 years

BUSINESS COMBINATIONS - Pro For

BUSINESS COMBINATIONS - Pro Forma Information (Details) - HemaCare Corporation $ in Thousands	3 Months Ended
	Mar. 28, 2020USD ($)
Business Acquisition [Line Items]
Revenue	$ 707,077
Net income attributable to common shareholders	$ 55,705

REVENUE FROM CONTRACTS WITH C_3

REVENUE FROM CONTRACTS WITH CUSTOMERS - Disaggregation of Revenues by Major Business Line (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Disaggregation of Revenue [Line Items]
Total revenue	$ 824,566	$ 707,059
RMS
Disaggregation of Revenue [Line Items]
Total revenue	176,910	145,996
RMS | Services and products transferred over time
Disaggregation of Revenue [Line Items]
Total revenue	64,896	60,041
RMS | Services and products transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenue	112,014	85,955
DSA
Disaggregation of Revenue [Line Items]
Total revenue	501,178	438,683
DSA | Services and products transferred over time
Disaggregation of Revenue [Line Items]
Total revenue	500,468	438,564
DSA | Services and products transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenue	710	119
Manufacturing
Disaggregation of Revenue [Line Items]
Total revenue	146,478	122,380
Manufacturing | Services and products transferred over time
Disaggregation of Revenue [Line Items]
Total revenue	50,568	37,314
Manufacturing | Services and products transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenue	$ 95,910	$ 85,066

REVENUE FROM CONTRACTS WITH C_4

REVENUE FROM CONTRACTS WITH CUSTOMERS - Schedule of Estimated Revenue Related to Performance Obligations (Details) $ in Thousands	Mar. 27, 2021USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	$ 350,232
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-03-28
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	$ 221,643
Performance obligations expected to be satisfied, expected timing	9 months 18 days
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	$ 124,063
Performance obligations expected to be satisfied, expected timing	2 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	$ 4,404
Performance obligations expected to be satisfied, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	$ 122
Performance obligations expected to be satisfied, expected timing	1 year
DSA
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	$ 338,338
DSA | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-03-28
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	212,919
DSA | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	120,893
DSA | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	4,404
DSA | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	122
Manufacturing
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	11,894
Manufacturing | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-03-28
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	8,724
Manufacturing | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	3,170
Manufacturing | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	0
Manufacturing | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	$ 0

REVENUE FROM CONTRACTS WITH C_5

REVENUE FROM CONTRACTS WITH CUSTOMERS - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020	Dec. 26, 2020
Revenue from Contract with Customer [Abstract]
Payment terms	30 days
Unpaid advanced client billings	$ 19,000		$ 16,000
Contract liabilities (customer contract deposits)	$ 36,652		$ 42,244
Percentage of unbilled revenue billed during period	60.00%	60.00%
Amount of unbilled revenue billed during period		$ 122,000
Percentage of contract liabilities recognized as revenue during period	60.00%	60.00%
Amount of contract liabilities recognized as revenue		$ 193,000

REVENUE FROM CONTRACTS WITH C_6

REVENUE FROM CONTRACTS WITH CUSTOMERS - Schedule of Client Receivables, Contract Assets and Contract Liabilities (Details) - USD ($) $ in Thousands	Mar. 27, 2021	Dec. 26, 2020
Revenue from Contract with Customer [Abstract]
Client receivables	$ 463,800	$ 489,042
Contract assets (unbilled revenue)	154,044	135,400
Contract liabilities (current and long-term deferred revenue)	233,075	227,417
Contract liabilities (customer contract deposits)	$ 36,652	$ 42,244

SEGMENT INFORMATION - Narrative

SEGMENT INFORMATION - Narrative (Details)	3 Months Ended
	Mar. 27, 2021segment
Segment Reporting [Abstract]
Number of reportable segments	3

SEGMENT INFORMATION - Revenue a

SEGMENT INFORMATION - Revenue and Other Financial Information by Reportable Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Segment Reporting Information [Line Items]
Revenue	$ 824,566	$ 707,059
Operating income	123,703	94,281
Depreciation and amortization	61,508	57,260
Capital expenditures	28,030	25,721
RMS
Segment Reporting Information [Line Items]
Revenue	176,910	145,996
Operating income	44,935	27,373
Depreciation and amortization	9,679	8,752
Capital expenditures	2,983	5,412
DSA
Segment Reporting Information [Line Items]
Revenue	501,178	438,683
Operating income	90,949	72,283
Depreciation and amortization	44,608	41,330
Capital expenditures	17,040	14,729
Manufacturing
Segment Reporting Information [Line Items]
Revenue	146,478	122,380
Operating income	49,437	41,112
Depreciation and amortization	6,569	6,366
Capital expenditures	$ 7,110	$ 5,161

SEGMENT INFORMATION - Reconcili

SEGMENT INFORMATION - Reconciliation of Segment Operating Income, Depreciation and Amortization, and Capital Expenditures (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Segment Reporting Information [Line Items]
Operating income	$ 123,703	$ 94,281
Depreciation and amortization	61,508	57,260
Capital expenditures	28,030	25,721
Total reportable segments
Segment Reporting Information [Line Items]
Operating income	185,321	140,768
Depreciation and amortization	60,856	56,448
Capital expenditures	27,133	25,302
Unallocated corporate
Segment Reporting Information [Line Items]
Operating income	(61,618)	(46,487)
Depreciation and amortization	652	812
Capital expenditures	$ 897	$ 419

SEGMENT INFORMATION - Revenue P

SEGMENT INFORMATION - Revenue Per Significant Product or Service (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Segment Reporting Information [Line Items]
Total revenue	$ 824,566	$ 707,059
RMS
Segment Reporting Information [Line Items]
Total revenue	176,910	145,996
DSA
Segment Reporting Information [Line Items]
Total revenue	501,178	438,683
Manufacturing
Segment Reporting Information [Line Items]
Total revenue	$ 146,478	$ 122,380

SEGMENT INFORMATION - Summary o

SEGMENT INFORMATION - Summary of Unallocated Corporate Overhead (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Segment Reporting Information [Line Items]
Stock-based compensation	$ 13,189	$ 10,960
Unallocated corporate
Segment Reporting Information [Line Items]
Stock-based compensation	7,642	6,704
Compensation, benefits, and other employee-related expenses	27,362	21,980
External consulting and other service expenses	7,356	2,469
Information technology	4,095	3,716
Depreciation	652	812
Acquisition and integration	10,560	6,983
Other general unallocated corporate	3,951	3,823
Total unallocated corporate expense	$ 61,618	$ 46,487

SEGMENT INFORMATION - Disaggreg

SEGMENT INFORMATION - Disaggregation of Revenue by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	$ 824,566	$ 707,059
UNITED STATES
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	448,482	406,712
Europe
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	237,535	190,262
Canada
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	77,107	76,633
Asia Pacific
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	59,446	31,829
Other
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenue	$ 1,996	$ 1,623

SUPPLEMENTAL BALANCE SHEET IN_3

SUPPLEMENTAL BALANCE SHEET INFORMATION (Details) - USD ($) $ in Thousands	Mar. 27, 2021	Dec. 26, 2020	Mar. 28, 2020
Composition of trade receivables
Client receivables	$ 463,800	$ 489,042
Unbilled revenue	154,044	135,400
Total	617,844	624,442
Less: Allowance for doubtful accounts	(7,278)	(6,702)
Trade receivables, net	610,566	617,740
Composition of inventories
Raw materials and supplies	26,726	28,317
Work in process	32,619	36,755
Finished products	134,239	120,623
Inventories	193,584	185,695
Composition of other current assets
Prepaid income tax	66,885	68,462
Short-term investments	1,025	1,024
Restricted cash	4,012	3,074	$ 444
Other current assets	71,922	72,560
Composition of other assets
Venture capital investments	175,506	197,100
Strategic equity investments	35,772	24,704
Life insurance policies	46,258	43,827
Other long-term income tax assets	22,827	23,485
Restricted cash	1,602	1,621	$ 1,576
Long-term pension assets	33,435	31,915
Other	34,031	29,974
Other assets	349,431	352,626
Composition of other current liabilities
Current portion of operating lease right-of-use liabilities	25,868	24,674
Accrued income taxes	24,952	24,884
Customer contract deposits	36,652	42,244
Other	9,875	10,675
Other current liabilities	97,347	102,477
Composition of other long-term liabilities
U.S. Transition Tax	48,781	48,781
Long-term pension liability, accrued executive supplemental life insurance retirement plan and deferred compensation plan	74,223	74,233
Long-term deferred revenue	20,043	19,475
Other	63,961	62,726
Other long-term liabilities	$ 207,008	$ 205,215

VENTURE CAPITAL AND STRATEGIC_2

VENTURE CAPITAL AND STRATEGIC EQUITY INVESTMENTS - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020	Dec. 26, 2020
Equity Method Investments and Joint Ventures [Abstract]
Venture capital investments	$ 175,506		$ 197,100
Committed contribution	149,300
Amount funded for venture capital investments	99,700
Distributions received	9,300	$ 900
Losses recognized	16,400	$ 12,200
Strategic equity investments	$ 35,772		$ 24,704

FAIR VALUE - Fair Value of Asse

FAIR VALUE - Fair Value of Assets and Liabilities (Details) - Fair Value, Recurring - USD ($) $ in Thousands	Mar. 27, 2021	Dec. 26, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 6,172	$ 2,273
Other assets:
Life insurance policies	38,250	35,770
Total assets measured at fair value	44,422	38,043
Other liabilities measured at fair value:
Contingent consideration	33,163	2,328
Total liabilities measured at fair value	33,163	2,328
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Other assets:
Life insurance policies	0	0
Total assets measured at fair value	0	0
Other liabilities measured at fair value:
Contingent consideration	0	0
Total liabilities measured at fair value	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	6,172	2,273
Other assets:
Life insurance policies	38,250	35,770
Total assets measured at fair value	44,422	38,043
Other liabilities measured at fair value:
Contingent consideration	0	0
Total liabilities measured at fair value	0	0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Other assets:
Life insurance policies	0	0
Total assets measured at fair value	0	0
Other liabilities measured at fair value:
Contingent consideration	33,163	2,328
Total liabilities measured at fair value	$ 33,163	$ 2,328

FAIR VALUE - Contingent Conside

FAIR VALUE - Contingent Consideration (Details) - Contingent Consideration - Level 3 - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 2,328	$ 712
Additions	29,990	2,131
Fair value adjustments	917	0
Payments	0	(218)
Foreign currency	(72)	(62)
Ending balance	$ 33,163	$ 2,563

FAIR VALUE - Schedule of Fair V

FAIR VALUE - Schedule of Fair Value of Debt (Details) - Senior Notes - USD ($) $ in Thousands	Mar. 27, 2021	Dec. 26, 2020	Dec. 28, 2019	Dec. 29, 2018
5.5% Senior Notes due 2026
Debt Instrument [Line Items]
Stated interest rate	5.50%	5.50%		5.50%
5.5% Senior Notes due 2026 | Book Value
Debt Instrument [Line Items]
Debt instrument value	$ 0	$ 500,000
5.5% Senior Notes due 2026 | Estimated Fair Value
Debt Instrument [Line Items]
Debt instrument value	$ 0	$ 523,100
4.25% Senior Notes due 2028
Debt Instrument [Line Items]
Stated interest rate	4.25%	4.25%	4.25%
4.25% Senior Notes due 2028 | Book Value
Debt Instrument [Line Items]
Debt instrument value	$ 500,000	$ 500,000
4.25% Senior Notes due 2028 | Estimated Fair Value
Debt Instrument [Line Items]
Debt instrument value	$ 513,750	$ 523,750
3.75% Senior Notes due 2029
Debt Instrument [Line Items]
Stated interest rate	3.75%	3.75%
3.75% Senior Notes due 2029 | Book Value
Debt Instrument [Line Items]
Debt instrument value	$ 500,000	$ 0
3.75% Senior Notes due 2029 | Estimated Fair Value
Debt Instrument [Line Items]
Debt instrument value	$ 501,250	$ 0
4.0% Senior Notes due 2031
Debt Instrument [Line Items]
Stated interest rate	4.00%	4.00%
4.0% Senior Notes due 2031 | Book Value
Debt Instrument [Line Items]
Debt instrument value	$ 500,000	$ 0
4.0% Senior Notes due 2031 | Estimated Fair Value
Debt Instrument [Line Items]
Debt instrument value	$ 504,350	$ 0

GOODWILL AND INTANGIBLE ASSET_2

GOODWILL AND INTANGIBLE ASSETS - Rollforward of Goodwill (Details) $ in Thousands	3 Months Ended
	Mar. 27, 2021USD ($)
Goodwill [Roll Forward]
Beginning balance	$ 1,809,168
Acquisitions	88,611
Foreign Exchange	(7,149)
Ending balance	1,890,630
RMS
Goodwill [Roll Forward]
Beginning balance	287,759
Acquisitions	0
Foreign Exchange	(169)
Ending balance	287,590
DSA
Goodwill [Roll Forward]
Beginning balance	1,378,130
Acquisitions	88,611
Foreign Exchange	(7,726)
Ending balance	1,459,015
Manufacturing
Goodwill [Roll Forward]
Beginning balance	143,279
Acquisitions	0
Foreign Exchange	746
Ending balance	$ 144,025

GOODWILL AND INTANGIBLE ASSET_3

GOODWILL AND INTANGIBLE ASSETS - Schedule of Intangible Assets (Details) - USD ($) $ in Thousands	Mar. 27, 2021	Dec. 26, 2020
Other intangible assets
Gross	$ 1,327,743	$ 1,334,244
Accumulated Amortization	(532,178)	(546,645)
Net	795,565	787,599
Backlog
Other intangible assets
Gross	610	29,233
Accumulated Amortization	(152)	(29,233)
Net	458	0
Technology
Other intangible assets
Gross	133,667	130,907
Accumulated Amortization	(85,610)	(81,305)
Net	48,057	49,602
Trademarks and trade names
Other intangible assets
Gross	12,231	15,870
Accumulated Amortization	(2,112)	(5,648)
Net	10,119	10,222
Other
Other intangible assets
Gross	28,736	20,903
Accumulated Amortization	(4,189)	(14,633)
Net	24,547	6,270
Other intangible assets
Other intangible assets
Gross	175,244	196,913
Accumulated Amortization	(92,063)	(130,819)
Net	83,181	66,094
Client relationships
Other intangible assets
Gross	1,152,499	1,137,331
Accumulated Amortization	(440,115)	(415,826)
Net	$ 712,384	$ 721,505

LONG-TERM DEBT AND FINANCE LE_3

LONG-TERM DEBT AND FINANCE LEASE OBLIGATIONS - Schedule of Long-Term Debt (Details) - USD ($) $ in Thousands	Mar. 27, 2021	Dec. 26, 2020	Dec. 28, 2019	Dec. 29, 2018
Debt Instrument [Line Items]
Long-term debt, gross	$ 2,194,504
Finance leases	28,844	$ 29,047
Total debt and finance leases	2,223,348	1,994,131
Current portion of long-term debt	109	47,196
Current portion of finance leases	2,823	3,018
Current portion of long-term debt and finance leases	2,932	50,214
Long-term debt and finance leases	2,220,416	1,943,917
Debt discount and debt issuance costs	(18,082)	(14,346)
Long-term debt, net and finance leases	2,202,334	1,929,571
Term Loans
Debt Instrument [Line Items]
Long-term debt, gross	0	146,875
Revolving Facility
Debt Instrument [Line Items]
Long-term debt, gross	$ 694,135	$ 814,752
Senior Notes | 5.5% Senior Notes due 2026
Debt Instrument [Line Items]
Stated interest rate	5.50%	5.50%		5.50%
Long-term debt, gross	$ 0	$ 500,000
Senior Notes | 4.25% Senior Notes due 2028
Debt Instrument [Line Items]
Stated interest rate	4.25%	4.25%	4.25%
Long-term debt, gross	$ 500,000	$ 500,000
Senior Notes | 3.75% Senior Notes due 2029
Debt Instrument [Line Items]
Stated interest rate	3.75%	3.75%
Long-term debt, gross	$ 500,000	$ 0
Senior Notes | 4.0% Senior Notes due 2031
Debt Instrument [Line Items]
Stated interest rate	4.00%	4.00%
Long-term debt, gross	$ 500,000	$ 0
Other Debt
Debt Instrument [Line Items]
Long-term debt, gross	$ 369	$ 3,457

LONG-TERM DEBT AND FINANCE LE_4

LONG-TERM DEBT AND FINANCE LEASE OBLIGATIONS - Narrative (Details)	Mar. 23, 2021USD ($)	Mar. 26, 2018	Apr. 30, 2021USD ($)	Mar. 27, 2021USD ($)payment	Mar. 28, 2020USD ($)	Dec. 26, 2020USD ($)	Dec. 28, 2019USD ($)	Dec. 29, 2018USD ($)
Debt Instrument [Line Items]
Weighted average interest rate				3.09%		3.11%
Deferred financing costs expensed				$ 28,680,000	$ 0
Debt extinguishment and financing costs				$ 26,907,000	0
Number of consecutive fiscal quarters				1 year
Credit Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Prepayments of long-term debt				$ 135,000,000
Term Loans
Debt Instrument [Line Items]
Prepayments of long-term debt				146,900,000
Deferred financing costs expensed				200,000
$750 Million Term Loan | Credit Facility
Debt Instrument [Line Items]
Credit facility				$ 750,000,000
Number of quarterly installment payments | payment				19
$2.05 Billion Credit Facility | Credit Facility
Debt Instrument [Line Items]
Minimum EBITDA less capital expenditures to consolidated cash interest expense ratio				3.50
$2.05 Billion Credit Facility | Credit Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Credit facility				$ 2,050,000,000
$2.05 Billion Credit Facility | Credit Facility | Revolving Credit Facility | Federal Funds Rate
Debt Instrument [Line Items]
Variable interest rate		0.50%
$2.05 Billion Credit Facility | Credit Facility | Revolving Credit Facility | LIBOR
Debt Instrument [Line Items]
Variable interest rate		1.00%
5.5% Senior Notes due 2026 | Senior Notes
Debt Instrument [Line Items]
Prepayments of long-term debt	$ 500,000,000
Deferred financing costs expensed	5,000,000
Aggregate principal amount								$ 500,000,000
Stated interest rate				5.50%		5.50%		5.50%
Debt extinguishment and financing costs	21,000,000
Payments for accrued interest	$ 13,000,000
4.25% Senior Notes due 2028 | Senior Notes
Debt Instrument [Line Items]
Maximum consolidated indebtedness to consolidated EBITDA				4.25
Aggregate principal amount							$ 500,000,000
Stated interest rate				4.25%		4.25%	4.25%
3.75% Senior Notes due 2029 | Senior Notes
Debt Instrument [Line Items]
Aggregate principal amount				$ 500,000,000
Stated interest rate				3.75%		3.75%
4.0% Senior Notes due 2031 | Senior Notes
Debt Instrument [Line Items]
Aggregate principal amount				$ 500,000,000
Stated interest rate				4.00%		4.00%
Letter of Credit
Debt Instrument [Line Items]
Letters of credit outstanding				$ 16,800,000		$ 16,000,000
$3 Billion Credit Facility | Credit Facility | Revolving Credit Facility | Subsequent Event
Debt Instrument [Line Items]
Credit facility			$ 3,000,000,000
$3 Billion Credit Facility | Credit Facility | Revolving Credit Facility | Federal Funds Rate | Subsequent Event
Debt Instrument [Line Items]
Variable interest rate			0.50%
$3 Billion Credit Facility | Credit Facility | Revolving Credit Facility | LIBOR | Subsequent Event
Debt Instrument [Line Items]
Variable interest rate			1.00%
Senior Notes Due 2029 And 2031 | Senior Notes
Debt Instrument [Line Items]
Aggregate principal amount				1,000,000,000
Debt extinguishment and financing costs				10,000,000
Senior Notes Due 2029 And 2031 | Senior Notes | Cognate BioServices, Inc.
Debt Instrument [Line Items]
Debt extinguishment and financing costs				21,000,000
Payments for accrued interest				13,000,000
Minimum | Foreign Exchange Forward
Debt Instrument [Line Items]
Derivative amount				300,000,000
Maximum | Foreign Exchange Forward
Debt Instrument [Line Items]
Derivative amount				400,000,000
Other Nonoperating Income (Expense) | Foreign Exchange Forward
Debt Instrument [Line Items]
Foreign currency losses recognized				13,400,000	4,200,000
Interest Expense | Foreign Exchange Forward
Debt Instrument [Line Items]
Recognized gains from derivatives				$ 13,977,000	$ 6,067,000

LONG-TERM DEBT AND FINANCE LE_5

LONG-TERM DEBT AND FINANCE LEASE OBLIGATIONS - Principal Maturities of Long Term Debt (Details) $ in Thousands	Mar. 27, 2021USD ($)
Debt Disclosure [Abstract]
2021 (excluding the three months ended March 27, 2021)	$ 109
2022	0
2023	0
2024	260
2025	0
Thereafter	2,194,135
Total	$ 2,194,504

EQUITY AND NONCONTROLLING INT_3

EQUITY AND NONCONTROLLING INTERESTS - Earnings Per Share (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Numerator:
Net income	$ 63,935	$ 50,837
Less: Net income attributable to noncontrolling interests	2,405	68
Net income attributable to common shareholders	$ 61,530	$ 50,769
Denominator:
Weighted-average shares outstanding—Basic (in shares)	49,980	49,189
Effect of dilutive securities:
Stock options, restricted stock units and performance share units (in shares)	1,095	777
Weighted-average shares outstanding—Diluted (in shares)	51,075	49,966

EQUITY AND NONCONTROLLING INT_4

EQUITY AND NONCONTROLLING INTERESTS - Narrative (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020	Feb. 29, 2020	Dec. 28, 2019	Apr. 29, 2019
Vital River
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Equity interest				92.00%
Noncontrolling interest ownership percentage	8.00%
Citoxlab
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Equity interest				90.00%
Noncontrolling interest ownership percentage				10.00%	10.00%
Supplier
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Equity interest				80.00%
Noncontrolling interest ownership percentage				20.00%
Employee Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share amount (in shares)	0.1	0.4
Restricted Stock and Restricted Stock Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share amount (in shares)	0.6	0.6
Vital River
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Contractually defined redemption value	$ 18.7
Citoxlab
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Contractually defined redemption value			$ 4

EQUITY AND NONCONTROLLING INT_5

EQUITY AND NONCONTROLLING INTERESTS - Treasury Shares (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Equity, Class of Treasury Stock [Line Items]
Shares acquired to satisfy minimum individual statutory tax withholdings for vesting of equity instruments (in shares)	100,000	100,000
Shares acquired to satisfy minimum individual statutory tax withholdings for vesting of equity instruments	$ 36	$ 23.7
Authorized Share Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Shares repurchased during period (in shares)	0	0
Remaining authorized repurchase amount	$ 129.1

EQUITY AND NONCONTROLLING INT_6

EQUITY AND NONCONTROLLING INTERESTS - Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Accumulated Other Comprehensive Income (Loss), before Tax [Roll Forward]
Beginning balance	$ 2,118,169	$ 1,637,828
Other comprehensive income before reclassifications	9,844
Amounts reclassified from accumulated other comprehensive income	988
Net current period other comprehensive income	10,832
Income tax (benefit) expense	(1,025)	(2,039)
Ending balance	2,188,184	1,655,627
Foreign Currency Translation Adjustment and Other
Accumulated Other Comprehensive Income (Loss), before Tax [Roll Forward]
Beginning balance	(73,884)
Other comprehensive income before reclassifications	9,844
Amounts reclassified from accumulated other comprehensive income	0
Net current period other comprehensive income	9,844
Income tax (benefit) expense	(1,270)
Ending balance	(62,770)
Pension and Other Post-Retirement Benefit Plans
Accumulated Other Comprehensive Income (Loss), before Tax [Roll Forward]
Beginning balance	(64,990)
Other comprehensive income before reclassifications	0
Amounts reclassified from accumulated other comprehensive income	988
Net current period other comprehensive income	988
Income tax (benefit) expense	245
Ending balance	(64,247)
Total
Accumulated Other Comprehensive Income (Loss), before Tax [Roll Forward]
Beginning balance	(138,874)	(178,019)
Ending balance	$ (127,017)	$ (218,917)

EQUITY AND NONCONTROLLING INT_7

EQUITY AND NONCONTROLLING INTERESTS - Rollforward of Redeemable Noncontrolling Interest (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020	Dec. 28, 2019	Apr. 29, 2019
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance	$ 25,499	$ 28,647
Adjustment to Vital River redemption value	835	0
Purchase of a 10% redeemable noncontrolling interest	0	(3,732)
Net income (loss) attributable to noncontrolling interests	1,716	(332)
Foreign currency translation	(15)	(544)
Ending balance	$ 28,035	$ 24,039
Citoxlab
Increase (Decrease) in Temporary Equity [Roll Forward]
Noncontrolling interest ownership percentage			10.00%	10.00%

INCOME TAXES (Details)

INCOME TAXES (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Income Tax Disclosure [Abstract]
Effective tax rate	3.60%	8.30%
Increase in unrecognized tax benefits	$ 0.3
Unrecognized tax benefits	25.3
Accrued interest on unrecognized tax benefits	2.4
Decrease in unrecognized tax benefits that are reasonably possibly over the next twelve-month period	$ 1

PENSION AND OTHER POST-RETIRE_3

PENSION AND OTHER POST-RETIREMENT BENEFIT PLANS - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Employee benefits
Service cost	$ 911	$ 797
Interest cost	1,344	2,355
Expected return on plan assets	(1,983)	(2,981)
Amortization of prior service cost (credit)	(128)	(125)
Amortization of net loss	1,110	1,586
Other adjustments	0	125
Net periodic cost	1,254	1,757
Other Postretirement Benefits Plan
Employee benefits
Net periodic cost	$ 0	$ 0

PENSION AND OTHER POST-RETIRE_4

PENSION AND OTHER POST-RETIREMENT BENEFIT PLANS - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Employee benefits
Net periodic cost	$ 1,254	$ 1,757
Other Postretirement Benefits Plan
Employee benefits
Net periodic cost	$ 0	$ 0

STOCK-BASED COMPENSATION - Stoc

STOCK-BASED COMPENSATION - Stock Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Stock-based compensation expense
Stock-based compensation, before income taxes	$ 13,189	$ 10,960
Provision for income taxes	(1,987)	(1,551)
Stock-based compensation, net of income taxes	11,202	9,409
Cost of revenue
Stock-based compensation expense
Stock-based compensation, before income taxes	2,713	2,035
Selling, general and administrative
Stock-based compensation expense
Stock-based compensation, before income taxes	$ 10,476	$ 8,925

FOREIGN CURRENCY CONTRACTS - Sc

FOREIGN CURRENCY CONTRACTS - Schedule of Derivative Instruments on Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Interest expense	$ (29,719)	$ (15,067)
Foreign Exchange Forward | Interest Expense
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss)	$ 13,977	$ 6,067

RESTRUCTURING AND ASSET IMPAI_3

RESTRUCTURING AND ASSET IMPAIRMENTS - Restructuring Costs by Classification on the Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 749	$ 559
Cost of services provided and products sold (excluding amortization of intangible assets)
Restructuring Cost and Reserve [Line Items]
Restructuring costs	563	476
Selling, general and administrative
Restructuring Cost and Reserve [Line Items]
Restructuring costs	186	83
Severance and Transition Costs
Restructuring Cost and Reserve [Line Items]
Restructuring costs	562	330
Severance and Transition Costs | Cost of services provided and products sold (excluding amortization of intangible assets)
Restructuring Cost and Reserve [Line Items]
Restructuring costs	523	247
Severance and Transition Costs | Selling, general and administrative
Restructuring Cost and Reserve [Line Items]
Restructuring costs	39	83
Asset Impairments and Other Costs
Restructuring Cost and Reserve [Line Items]
Restructuring costs	187	229
Asset Impairments and Other Costs | Cost of services provided and products sold (excluding amortization of intangible assets)
Restructuring Cost and Reserve [Line Items]
Restructuring costs	40	229
Asset Impairments and Other Costs | Selling, general and administrative
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 147	$ 0

RESTRUCTURING AND ASSET IMPAI_4

RESTRUCTURING AND ASSET IMPAIRMENTS - Restructuring Costs by Reportable Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Segment Reporting Information [Line Items]
Restructuring costs	$ 749	$ 559
Unallocated corporate
Segment Reporting Information [Line Items]
Restructuring costs	(151)	0
RMS
Segment Reporting Information [Line Items]
Restructuring costs	7	220
DSA
Segment Reporting Information [Line Items]
Restructuring costs	559	83
Manufacturing
Segment Reporting Information [Line Items]
Restructuring costs	$ 334	$ 256

RESTRUCTURING AND ASSET IMPAI_5

RESTRUCTURING AND ASSET IMPAIRMENTS - Rollforward of Severance and Transition Costs Liability (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Restructuring Reserve [Roll Forward]
Beginning balance	$ 5,816	$ 6,406
Expense (excluding non-cash charges)	749	517
Payments / utilization	(2,465)	(4,243)
Other non-cash adjustments	(1,831)	0
Foreign currency adjustments	(48)	(149)
Ending balance	$ 2,221	$ 2,531

RESTRUCTURING AND ASSET IMPAI_6

RESTRUCTURING AND ASSET IMPAIRMENTS - Narrative (Details) - USD ($) $ in Thousands	Mar. 27, 2021	Dec. 26, 2020	Mar. 28, 2020	Dec. 28, 2019
Restructuring Cost and Reserve [Line Items]
Severance and other personnel related costs liability and lease obligation liabilities	$ 2,221	$ 5,816	$ 2,531	$ 6,406
Severance and Transition Costs | Accrued Compensation and Accrued Liabilities
Restructuring Cost and Reserve [Line Items]
Severance and other personnel related costs liability and lease obligation liabilities	$ 2,200		2,400
Severance and Transition Costs | Other Long-Term Liabilities
Restructuring Cost and Reserve [Line Items]
Severance and other personnel related costs liability and lease obligation liabilities			$ 100

LEASES - Right-of-Use Lease Ass

LEASES - Right-of-Use Lease Assets and Lease Liabilities in Condensed Consolidated Financial Statements (Details) - USD ($) $ in Thousands	Mar. 27, 2021	Dec. 26, 2020
Leases [Abstract]
Operating lease right-of-use assets, net	$ 197,668	$ 178,220
Other current liabilities	25,868	24,674
Operating lease right-of-use liabilities	173,015	155,595
Total operating lease liabilities	198,883	180,269
Property, plant and equipment, net	31,437	31,614
Current portion of long-term debt and finance leases	2,823	3,018
Long-term debt, net and finance leases	26,021	26,029
Total finance lease liabilities	$ 28,844	$ 29,047
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Other current liabilities	Other current liabilities
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Property, plant and equipment, net	Property, plant and equipment, net
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	Current portion of long-term debt and finance leases	Current portion of long-term debt and finance leases
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Long-term debt, net and finance leases	Long-term debt, net and finance leases

LEASES - Components of Operatin

LEASES - Components of Operating and Finance Lease Costs (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Leases [Abstract]
Operating lease costs	$ 9,352	$ 8,077
Amortization of right-of-use assets	848	951
Interest on lease liabilities	328	340
Short-term lease costs	950	589
Variable lease costs	883	1,045
Sublease income	(374)	(586)
Total lease costs	$ 11,987	$ 10,416

LEASES - Supplemental Cash Flow

LEASES - Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Cash flows included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 8,503	$ 6,974
Operating cash flows from finance leases	328	340
Finance cash flows from finance leases	942	1,572
Non-cash leases activity:
Right-of-use lease assets obtained in exchange for new operating lease liabilities	25,968	25,407
Right-of-use lease assets obtained in exchange for new finance lease liabilities	$ 86	$ 593

LEASES - Weighted Average Remai

LEASES - Weighted Average Remaining Lease Term and Discount Rates (Details)	Mar. 27, 2021	Mar. 28, 2020
Weighted-average remaining lease term (in years)
Operating lease	8 years 8 months 12 days	8 years 4 months 24 days
Finance lease	12 years 4 months 24 days	12 years 8 months 12 days
Weighted-average discount rate
Operating lease	3.90%	4.20%
Finance lease	4.50%	4.50%

LEASES - Schedule of Future Min

LEASES - Schedule of Future Minimum Lease Payments (Details) - USD ($) $ in Thousands	Mar. 27, 2021	Dec. 26, 2020
Operating Leases, After Adoption of 842
2021 (excluding the three months ended March 27, 2021)	$ 24,996
2022	30,659
2023	28,248
2024	27,113
2025	24,635
Thereafter	101,665
Total minimum future lease payments	237,316
Less: Imputed interest	38,433
Total lease liabilities	198,883	$ 180,269
Finance Leases, After Adoption of 842
2021 (excluding the three months ended March 27, 2021)	3,078
2022	3,738
2023	3,411
2024	3,181
2025	2,902
Thereafter	21,597
Total minimum future lease payments	37,907
Less: Imputed interest	9,063
Total lease liabilities	$ 28,844	$ 29,047

LEASES - Narrative (Details)

LEASES - Narrative (Details) $ in Millions	Mar. 27, 2021USD ($)
Lessor, Lease, Description [Line Items]
Future minimum lease payments for leases that have not yet commenced	$ 108
Minimum
Lessor, Lease, Description [Line Items]
Terms for leases that have not yet commenced	8 years
Maximum
Lessor, Lease, Description [Line Items]
Terms for leases that have not yet commenced	15 years