GOODWILL AND INTANGIBLE ASSETS (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Gross (Excluding Goodwill)	$ 5,443.5		$ 5,443.5		$ 5,058.4
Goodwill	6,482.4		6,482.4		6,142.5
Amortization of intangibles and other assets	63.7	$ 55.7	186.0	$ 160.6
Adjustments to goodwill			(9.6)
Estimated amortization expense, 2013	260.4		260.4
Estimated amortization expense, 2014	251.4		251.4
Estimated amortization expense, 2015	240.1		240.1
Estimated amortization expense, 2016	232.2		232.2
Estimated amortization expense, Thereafter	1,915.4		1,915.4
Current Expected Credit Losses Opening Balance Sheet Impact on Retained Earnings			7.7
Amortization of intangible assets	63.7	$ 55.7	186.0	$ 160.6
LabCorp Diagnostics [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill	5,153.9		5,153.9		4,813.9
Adjustments to goodwill			(9.5)
Covance Drug Development [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 1,328.5		1,328.5		$ 1,328.6
Adjustments to goodwill			$ (0.1)