BASIS OF FINANCIAL STATEMENT PRESENTATION (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Asset Impairment Charges	$ 10.2			$ 0.0			$ 15.2	$ 1.2
Revenues	3,056.8			$ 2,866.8			9,128.3	$ 8,934.2
Contract with Customer, Liability	$ 360.8						$ 360.8		$ 310.6
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	$ 55.1			$ 38.2			$ 168.8	$ 260.8
Net Income (Loss) Attributable to Parent	183.3	$ 188.9	$ 212.9	352.8	$ 358.6	$ 491.6	585.1	1,203.0
Stockholders' Equity Attributable to Parent	7,873.1	$ 8,785.0	$ 10,341.5	10,092.2	$ 10,400.7	$ 10,721.1	7,873.1	10,092.2	10,096.6	$ 10,273.4
Deferred Revenue, Revenue Recognized	6.3			$ 9.3			79.1	$ 65.9
Cash and cash equivalents	$ 727.9						$ 727.9		$ 320.6
LabCorp Diagnostics [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percent of Revenue Contributed	77.00%			77.00%			77.00%	77.00%