BUSINESS SEGMENT INFORMATION Business Segment Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Segment Reporting Information [Line Items]
Percent of Revenue Contributed	100.00%	100.00%
Revenues	$ 3,777.9	$ 3,899.6
Operating Income (Loss)	341.0	687.9
Amortization of Intangible Assets	(69.3)	(67.1)
Net Restructuring Charges	(8.6)	(12.6)
Goodwill and Intangible Asset Impairment	(2.2)	(1.2)
Operating Segments
Segment Reporting Information [Line Items]
Operating Income (Loss)	565.4	851.7
Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenues	6.2	13.8
Corporate Segment [Member]
Segment Reporting Information [Line Items]
Operating Income (Loss)	$ (144.3)	$ (82.9)
LabCorp Diagnostics [Member]
Segment Reporting Information [Line Items]
Percent of Revenue Contributed	63.00%	63.00%
Diagnostics
Segment Reporting Information [Line Items]
Percent of Revenue Contributed	63.00%
Diagnostics | Operating Segments
Segment Reporting Information [Line Items]
Revenues	$ 2,382.8	$ 2,454.1
Operating Income (Loss)	$ 441.5	683.1
Drug Development
Segment Reporting Information [Line Items]
Percent of Revenue Contributed	37.00%
Drug Development | Operating Segments
Segment Reporting Information [Line Items]
Revenues	$ 1,401.3	1,459.3
Operating Income (Loss)	$ 123.9	$ 168.6