BUSINESS SEGMENT INFORMATION (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Property, plant and equipment, net	$ 2,815.4	$ 2,729.6
Depreciation and amortization:
Depreciation and amortization	745.1	624.7	$ 577.2
Depreciation and Amortization of Intangible Assets			564.7
Revenues	16,120.9	13,978.5	11,554.8
Operating Income (Loss)	3,259.5	2,445.4	1,330.2
Total pre-tax income	3,126.6	2,219.1	1,104.9
Provision for income taxes	747.1	662.1	280.0
Net earnings	2,379.5	1,557.0	824.9
Net Income (Loss) Attributable to Noncontrolling Interest	(2.2)	(0.9)	(1.1)
Net earnings attributable to Laboratory Corporation of America Holdings	2,377.3	1,556.1	823.8
Intersegment Eliminations
Depreciation and amortization:
Revenues	88.2	152.6	23.4
LabCorp Diagnostics [Member] | Operating Segments
Segment Reporting Information [Line Items]
Property, plant and equipment, net	1,507.3
Depreciation and amortization:
Depreciation and amortization	355.8	327.5	301.0
Revenues	10,363.6	9,253.4	7,000.1
Operating Income (Loss)	2,988.5	2,634.9	1,086.0
Covance Drug Development [Member] | Operating Segments
Segment Reporting Information [Line Items]
Property, plant and equipment, net	1,308.1
Depreciation and amortization:
Depreciation and amortization	386.7	295.2	261.1
Revenues	5,845.5	4,877.7	4,578.1
Operating Income (Loss)	547.7	37.3	411.5
Corporate Segment [Member]
Depreciation and amortization:
Depreciation and amortization	2.6	2.0	2.6
Operating Income (Loss)	(276.7)	$ (226.8)	$ (167.3)
Other countries [Member]
Segment Reporting Information [Line Items]
Property, plant and equipment, net	188.0
Depreciation and amortization:
Revenues	976.4
Other countries [Member] | Intersegment Eliminations
Depreciation and amortization:
Revenues	0.0
Other countries [Member] | LabCorp Diagnostics [Member] | Operating Segments
Segment Reporting Information [Line Items]
Property, plant and equipment, net	0.0
Depreciation and amortization:
Revenues	0.0
Other countries [Member] | Covance Drug Development [Member] | Operating Segments
Segment Reporting Information [Line Items]
Property, plant and equipment, net	188.0
Depreciation and amortization:
Revenues	976.4
North America
Segment Reporting Information [Line Items]
Property, plant and equipment, net	2,177.5
Depreciation and amortization:
Revenues	13,093.7
North America | LabCorp Diagnostics [Member] | Operating Segments
Segment Reporting Information [Line Items]
Property, plant and equipment, net	1,507.3
Depreciation and amortization:
Revenues	10,363.6
North America | Covance Drug Development [Member] | Operating Segments
Segment Reporting Information [Line Items]
Property, plant and equipment, net	670.2
Depreciation and amortization:
Revenues	2,818.3
Europe [Member]
Segment Reporting Information [Line Items]
Property, plant and equipment, net	449.9
Depreciation and amortization:
Revenues	2,050.8
Europe [Member] | Intersegment Eliminations
Depreciation and amortization:
Revenues	0.0
Europe [Member] | LabCorp Diagnostics [Member] | Operating Segments
Segment Reporting Information [Line Items]
Property, plant and equipment, net	0.0
Depreciation and amortization:
Revenues	0.0
Europe [Member] | Covance Drug Development [Member] | Operating Segments
Segment Reporting Information [Line Items]
Property, plant and equipment, net	449.9
Depreciation and amortization:
Revenues	$ 2,050.8