RESTRUCTURING AND OTHER CHARGES - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restructuring Cost and Reserve [Line Items]
Net restructuring charges	$ 40.6	$ 54.6	$ 48.1
Restructuring charges related to severance and other employee costs	14.1	32.9	40.3
Restructuring charges related to contractual obligations associated with leased facilities and other facility related costs	18.9	24.9	11.8
Restructuring, Settlement and Impairment Provisions			2.3
Reduction in prior employee severance benefits related restructuring accruals	0.6	1.7	2.0
Reduction in prior facility related restructuring accruals	$ 9.2	1.5	2.0
Number of years restructuring liabilities expected to be paid out over	4 years 10 months 24 days
Covance Drug Development [Member]
Restructuring Cost and Reserve [Line Items]
Net restructuring charges	$ 25.3	27.9	27.6
LabCorp Diagnostics [Member]
Restructuring Cost and Reserve [Line Items]
Net restructuring charges	$ 15.3	$ 26.7	$ 20.5