GOODWILL AND INTANGIBLE ASSETS (Changes in Carrying Amount of Goodwill) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Goodwill [Line Items]
Severance Costs	$ 4.5	$ 3.2
Intangible Assets, Gross (Excluding Goodwill)	4,480.6		$ 4,356.0
Balance as of January 1	6,191.9	3,099.4
Goodwill, Acquired During Period	59.4	3,194.6
Adjustments to goodwill	1.1	(102.1)
Balance at end of period	6,252.4
Finite-Lived Intangible Assets, Accumulated Amortization	1,070.2		1,023.6
Intangible Assets, Net (Excluding Goodwill)	3,410.4		3,332.4
LabCorp Diagnostics [Member]
Goodwill [Line Items]
Balance as of January 1	3,201.7	2,988.9
Goodwill, Acquired During Period	59.4	225.6
Adjustments to goodwill	(21.1)	(12.8)
Balance at end of period	3,240.0
Covance Drug Development [Member]
Goodwill [Line Items]
Balance as of January 1	2,990.2	110.5
Goodwill, Acquired During Period	0.0	2,969.0
Adjustments to goodwill	22.2	$ (89.3)
Balance at end of period	3,012.4
Customer Relationships [Member]
Goodwill [Line Items]
Intangible Assets, Gross (Excluding Goodwill)	3,220.7		3,137.8
Finite-Lived Intangible Assets, Accumulated Amortization	758.1		725.6
Intangible Assets, Net (Excluding Goodwill)	2,462.6		2,412.2
Patents, Licenses And Technology [Member]
Goodwill [Line Items]
Intangible Assets, Gross (Excluding Goodwill)	322.2		309.6
Finite-Lived Intangible Assets, Accumulated Amortization	150.9		144.7
Intangible Assets, Net (Excluding Goodwill)	171.3		164.9
Noncompete Agreements [Member]
Goodwill [Line Items]
Intangible Assets, Gross (Excluding Goodwill)	49.8		51.2
Finite-Lived Intangible Assets, Accumulated Amortization	38.3		37.2
Intangible Assets, Net (Excluding Goodwill)	11.5		14.0
Trade Names [Member]
Goodwill [Line Items]
Intangible Assets, Gross (Excluding Goodwill)	402.8		400.9
Finite-Lived Intangible Assets, Accumulated Amortization	122.1		115.5
Intangible Assets, Net (Excluding Goodwill)	280.7		285.4
Use Rights [Member]
Goodwill [Line Items]
Intangible Assets, Gross (Excluding Goodwill)	5.5		5.5
Finite-Lived Intangible Assets, Accumulated Amortization	0.8		0.6
Intangible Assets, Net (Excluding Goodwill)	4.7		4.9
Canadian licenses [Member]
Goodwill [Line Items]
Intangible Assets, Gross (Excluding Goodwill)	479.6		451.0
Finite-Lived Intangible Assets, Accumulated Amortization	0.0		0.0
Intangible Assets, Net (Excluding Goodwill)	$ 479.6		$ 451.0

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of increase (decrease) from foreign currency translation adjustments and purchase accounting adjustments of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount before accumulated amortization of intangible assets, excluding goodwill.

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