REVENUES - ACCOUNTS RECEIVABLES, UNBILLED SERVICES, AND UNEARNED REVENUE (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross unbilled services	$ 160.5	$ 192.9
Less reserve for unbilled services	(7.6)	(7.5)
Contract with Customer, Asset, after Allowance for Credit Loss, Current	152.9	185.4
Unearned revenue	392.2	421.7
Deferred Revenue, Revenue Recognized	113.0	78.9	$ 99.7
Accounts Receivable, Allowance for Credit Loss	(44.7)	(32.7)	(30.8)
Allowance for Credit Loss	(52.3)	(40.2)	(41.3)
Accounts Receivable, Credit Loss Expense (Reversal)	14.6	6.3
Accounts Receivable, Allowance for Credit Loss, Writeoff	(2.2)	(4.4)
Unbilled Services, Allowance for Credit Loss	(7.6)	(7.5)	$ (10.5)
Unbilled Services, Credit Loss Expense (Reversal)	0.1	0.0
Unbilled Services, Allowance for Credit Loss, Write Off	0.0	3.0
Unbilled Services, Allowance for Credit Loss, Write Off	0.0	(3.0)
Credit Loss Expense (Reversal)	14.7	6.3
Accounts Receivable, Allowance for Credit Loss, Writeoff	(2.2)	(7.4)
Financing Receivable, Allowance for Credit Loss, Foreign Currency Translation	0.4
Accounts receivable, net	1,944.1	1,913.3
LabCorp Diagnostics [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, before Allowance for Credit Loss	1,259.3	1,135.2
Biopharma Laboratory Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, before Allowance for Credit Loss	729.5	810.8
Accounts Receivable, Allowance for Credit Loss	$ (44.7)	$ (32.7)