REVENUE Disaggregated Revenue Table (Details) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Accounts Receivable, Allowance for Credit Loss	$ 19,400,000		$ 21,500,000
Unbilled Services, Allowance for Credit Loss	13,200,000		13,900,000
Note Receivable, Allowance for Credit Loss	700,000		700,000
Allowance for Credit Loss	33,300,000		36,100,000
Current Expected Credit Losses Opening Balance Sheet Impact on Retained Earnings	(400,000)
Allowance for Credit Loss, Write Off	2,400,000
Deferred Revenue, Revenue Recognized	163,800,000	$ 152,300,000
Contract with Customer, Asset, before Allowance for Credit Loss	813,200,000		730,800,000
Revenue, Remaining Performance Obligation, Amount	$ 6,069,800,000	5,563,400,000
Long Term Contracts Duration Minimum	1 year
Long Term Contracts Duration Maximum	8 years
Contract with Customer, Performance Obligation Satisfied in Previous Period	$ 31,700,000	16,500,000
Contract with Customer, Liability	556,000,000.0		558,500,000
Capitalized Contract Cost, Amortization	3,100,000	3,500,000
Accrued Sales Commission	38,800,000		36,200,000
Capitalized Contract Cost, Net	14,900,000		14,400,000
Amount of Deferred Costs Related to Long-term Contracts	53,700,000		50,600,000
Amortization of Deferred Sales Commissions	7,200,000	$ 6,900,000
Unbilled Contracts Receivable	$ 800,000,000.0		716,800,000
Percent of Revenue Contributed	100.00%	100.00%
Revenues	$ 3,899,600,000	$ 4,161,500,000
Accounts Receivable, after Allowance for Credit Loss, Current	2,239,600,000		2,261,500,000
Allowance for Credit Loss, Receivable, Other, Current	(13,200,000)		(14,000,000.0)
Contract with Customer, Asset, after Allowance for Credit Loss, Current	$ 800,000,000.0		716,800,000
Europe [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	13.00%	10.00%
North America
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	80.00%	86.00%
Other countries [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	7.00%	4.00%
UNITED STATES
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	76.90%	83.40%
Revenues	$ 3,000,500,000	$ 3,472,500,000
Medicare and Medicaid [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	6.00%	7.00%
LabCorp Diagnostics [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	63.00%	65.00%
Revenues	$ 2,454,100,000	$ 2,757,800,000
LabCorp Diagnostics [Member] | Europe [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	0.00%	0.00%
LabCorp Diagnostics [Member] | North America
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	63.00%	65.00%
LabCorp Diagnostics [Member] | Other countries [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	0.00%	0.00%
LabCorp Diagnostics [Member] | Client [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	17.00%	19.00%
LabCorp Diagnostics [Member] | Client [Member] | Europe [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	0.00%	0.00%
LabCorp Diagnostics [Member] | Client [Member] | North America
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	17.00%	19.00%
LabCorp Diagnostics [Member] | Client [Member] | Other countries [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	0.00%	0.00%
LabCorp Diagnostics [Member] | Self-Pay [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	5.00%	5.00%
LabCorp Diagnostics [Member] | Self-Pay [Member] | Europe [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	0.00%	0.00%
LabCorp Diagnostics [Member] | Self-Pay [Member] | North America
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	5.00%	5.00%
LabCorp Diagnostics [Member] | Self-Pay [Member] | Other countries [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	0.00%	0.00%
LabCorp Diagnostics [Member] | Medicare and Medicaid [Member] | Europe [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	0.00%	0.00%
LabCorp Diagnostics [Member] | Medicare and Medicaid [Member] | North America
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	6.00%	7.00%
LabCorp Diagnostics [Member] | Medicare and Medicaid [Member] | Other countries [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	0.00%	0.00%
LabCorp Diagnostics [Member] | Third party [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	35.00%	34.00%
LabCorp Diagnostics [Member] | Third party [Member] | Europe [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	0.00%	0.00%
LabCorp Diagnostics [Member] | Third party [Member] | North America
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	35.00%	34.00%
LabCorp Diagnostics [Member] | Third party [Member] | Other countries [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	0.00%	0.00%
Covance Drug Development [Member]
Disaggregation of Revenue [Line Items]
Revenues	$ 1,459,300,000	$ 1,438,200,000
Covance Drug Development [Member] | Biopharmaceutical and medical device companies [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed		35.00%
Covance Drug Development [Member] | Biopharmaceutical and medical device companies [Member] | Europe [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed		10.00%
Covance Drug Development [Member] | Biopharmaceutical and medical device companies [Member] | North America
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed		21.00%
Covance Drug Development [Member] | Biopharmaceutical and medical device companies [Member] | Other countries [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed		4.00%
Diagnostics
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	63.00%
Accounts Receivable, before Allowance for Credit Loss	$ 1,155,200,000		1,193,800,000
Drug Development
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	37.00%
Accounts Receivable, before Allowance for Credit Loss	$ 1,103,800,000		$ 1,089,200,000
Drug Development | Biopharmaceutical and medical device companies [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	37.00%
Drug Development | Biopharmaceutical and medical device companies [Member] | Europe [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	13.00%
Drug Development | Biopharmaceutical and medical device companies [Member] | North America
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	17.00%
Drug Development | Biopharmaceutical and medical device companies [Member] | Other countries [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue Contributed	7.00%
Notes Receivable [Member]
Disaggregation of Revenue [Line Items]
Current Expected Credit Losses Opening Balance Sheet Impact on Retained Earnings	$ 0
Allowance for Credit Loss, Write Off	0
Unbilled Contracts Receivable [Member]
Disaggregation of Revenue [Line Items]
Current Expected Credit Losses Opening Balance Sheet Impact on Retained Earnings	0
Allowance for Credit Loss, Write Off	700,000
Accounts Receivable [Member]
Disaggregation of Revenue [Line Items]
Current Expected Credit Losses Opening Balance Sheet Impact on Retained Earnings	(400,000)
Allowance for Credit Loss, Write Off	$ 1,700,000