GOODWILL AND INTANGIBLE ASSETS (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 219,800,000	$ 193,600,000	$ 229,500,000
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Asset		68,300,000
Finite-Lived Intangible Assets, Future Amortization Expense
Estimated amortization expense, 2013	235,400,000
Estimated amortization expense, 2014	225,700,000
Estimated amortization expense, 2015	216,800,000
Estimated amortization expense, 2016	205,500,000
Estimated amortization expense, 2017	197,300,000
Estimated amortization expense, Thereafter	1,675,000,000
Goodwill, Impairment Loss	333,600,000	260,000,000.0
Goodwill and Intangible Asset Impairment	349,000,000.0	261,700,000	$ 0
Goodwill Impairment, Cumulative	648,500,000
Covance Drug Development [Member]
Finite-Lived Intangible Assets, Future Amortization Expense
Goodwill, Impairment Loss	333,600,000	260,000,000.0
Goodwill and Intangible Asset Impairment	333,600,000
Covance Drug Development [Member] | Trademarks and Trade Names [Member]
Finite-Lived Intangible Assets, Future Amortization Expense
Amortization	30.8
LabCorp Diagnostics [Member]
Finite-Lived Intangible Assets, Future Amortization Expense
Goodwill, Impairment Loss	$ 0	$ 0