EARNINGS PER SHARE (Reconciliation of Basic Earnings Per Share to Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Income [Abstract]
Net earnings attributable to Laboratory Corporation of America Holdings	$ 155.0	$ 267.7	$ 363.0	$ 688.3
Shares [Abstract]
Net earnings, basic (in shares)	88.7	92.3	88.6	92.7
Dilutive effect of employee stock options and awards, (in shares)	0.3	0.4	0.4	0.6
Income (Loss) from Continuing Operations, Per Diluted Share	$ 1.74	$ 2.89	$ 4.08	$ 7.38
Per Share Amount [Abstract]
Net Income (Loss) Available to Common Stockholders, Diluted	$ 155.0	$ 267.7	$ 363.0	$ 688.3
Weighted Average Number of Shares Outstanding, Diluted	89.0	92.7	89.0	93.3
Income (Loss) from Continuing Operations, Per Basic Share	$ 1.75	$ 2.90	$ 4.10	$ 7.43