BASIS OF FINANCIAL STATEMENT PRESENTATION (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Asset Impairment Charges	$ 0.0		$ 2.8		$ 2.5	$ 5.0
Revenues	3,220.9		$ 3,033.7		6,397.5	$ 6,071.5
Contract with Customer, Liability	$ 388.3				$ 388.3		$ 421.7
Percent of Revenue Contributed	100.00%		100.00%		100.00%	100.00%
Ownership percentage below which investments are generally accounted for on the cost method (in thousandths)					20.00%
Provision for income taxes	$ 62.1		$ 49.8		$ 131.2	$ 113.7
Net Income (Loss) Attributable to Parent	205.3	$ 228.0	188.9	$ 212.9	433.3	401.8
Stockholders' Equity Attributable to Parent	8,005.8	$ 7,959.6	10,341.5	$ 8,785.0	8,005.8	10,341.5	7,875.0	$ 10,096.6
Deferred Revenue, Revenue Recognized	26.8		$ 20.2		77.8	$ 72.8
Cash and cash equivalents	$ 265.1				$ 265.1		$ 536.8
LabCorp Diagnostics [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percent of Revenue Contributed	78.00%		77.00%		78.00%	78.00%