BUSINESS SEGMENT INFORMATION Business Segment Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Segment Reporting Information [Line Items]
Percent of Revenue Contributed	100.00%	100.00%
Intercompany revenue elimination	$ (13.8)	$ (34.5)
Revenues	3,899.6	4,161.5
Operating Income (Loss)	687.9	1,057.9
Corporate Segment [Member]
Segment Reporting Information [Line Items]
Operating Income (Loss)	$ (59.6)	$ (47.6)
LabCorp Diagnostics [Member]
Segment Reporting Information [Line Items]
Percent of Revenue Contributed	63.00%	65.00%
Revenues	$ 2,454.1	$ 2,757.8
Operating Income (Loss)	623.3	949.1
Covance Drug Development [Member]
Segment Reporting Information [Line Items]
Revenues	1,459.3	1,438.2
Operating Income (Loss)	$ 124.2	$ 156.4