GOODWILL AND INTANGIBLE ASSETS (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Gross (Excluding Goodwill)	$ 5,149.2		$ 5,058.4
Goodwill	6,218.9		6,142.5
Amortization of intangibles and other assets	60.1	$ 53.4
Adjustments to goodwill	(65.3)
Estimated amortization expense, 2013	237.3
Estimated amortization expense, 2014	228.4
Estimated amortization expense, 2015	217.1
Estimated amortization expense, 2016	209.0
Estimated amortization expense, Thereafter	1,737.4
Current Expected Credit Losses Opening Balance Sheet Impact on Retained Earnings	2.4
Amortization of intangible assets	60.1	$ 53.4
LabCorp Diagnostics [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill	4,946.2		4,813.9
Adjustments to goodwill	(9.4)
Covance Drug Development [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill	1,272.7		$ 1,328.6
Adjustments to goodwill	$ (55.9)

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The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Amount of amortization for asset, excluding financial asset and goodwill, lacking physical substance with finite life expected to be recognized after fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount before accumulated amortization of intangible assets, excluding goodwill.

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