GOODWILL AND INTANGIBLE ASSETS - SCHEDULE OF GOODWILL (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Goodwill [Line Items]
Goodwill	$ 6,142,500,000	$ 6,123,700,000	$ 5,891,000,000
Adjustments to goodwill	55,500,000	(105,800,000)
Goodwill, Acquired During Period	296,900,000	598,500,000	298,400,000
Goodwill, Impairment Loss	(333,600,000)	(260,000,000.0)
Goodwill [Roll Forward]
Balance as of January 1	6,123,700,000	5,891,000,000
Adjustments to goodwill	55,500,000	(105,800,000)
Goodwill, net	6,142,500,000	6,123,700,000	5,891,000,000
LabCorp Diagnostics [Member]
Goodwill [Line Items]
Goodwill	4,813,900,000	4,533,500,000	4,046,200,000
Adjustments to goodwill	(16,500,000)	(70,600,000)
Goodwill, Acquired During Period	296,900,000	557,900,000
Goodwill, Impairment Loss	0	0
Goodwill [Roll Forward]
Balance as of January 1	4,533,500,000	4,046,200,000
Adjustments to goodwill	(16,500,000)	(70,600,000)
Goodwill, net	4,813,900,000	4,533,500,000	4,046,200,000
Covance Drug Development [Member]
Goodwill [Line Items]
Goodwill	1,328,600,000	1,590,200,000	1,844,800,000
Adjustments to goodwill	72,000,000.0	(35,200,000)
Goodwill, Acquired During Period	0	40,600,000
Goodwill, Impairment Loss	(333,600,000)	(260,000,000.0)
Goodwill [Roll Forward]
Balance as of January 1	1,590,200,000	1,844,800,000
Adjustments to goodwill	72,000,000.0	(35,200,000)
Goodwill, net	$ 1,328,600,000	$ 1,590,200,000	$ 1,844,800,000