GOODWILL AND INTANGIBLE ASSETS (Changes in Carrying Amount of Goodwill) (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Goodwill [Line Items]
Severance Costs	$ 9.0	$ 9.5
Intangible Assets, Gross (Excluding Goodwill)	4,473.5		$ 4,356.0
Balance as of January 1	6,191.9	3,099.4	3,099.4
Goodwill, Acquired During Period	87.2		3,194.6
Adjustments to goodwill	(60.8)		(102.1)
Balance at end of period	6,218.3		6,191.9
Finite-Lived Intangible Assets, Accumulated Amortization	1,115.6		1,023.6
Intangible Assets, Net (Excluding Goodwill)	3,357.9		3,332.4
LabCorp Diagnostics [Member]
Goodwill [Line Items]
Balance as of January 1	3,201.7	2,988.9	2,988.9
Goodwill, Acquired During Period	87.2		225.6
Adjustments to goodwill	49.3		(12.8)
Balance at end of period	3,338.2		3,201.7
Covance Drug Development [Member]
Goodwill [Line Items]
Balance as of January 1	2,990.2	$ 110.5	110.5
Goodwill, Acquired During Period	0.0		2,969.0
Adjustments to goodwill	(110.1)		(89.3)
Balance at end of period	2,880.1		2,990.2
Customer Relationships [Member]
Goodwill [Line Items]
Intangible Assets, Gross (Excluding Goodwill)	3,213.9		3,137.8
Finite-Lived Intangible Assets, Accumulated Amortization	791.0		725.6
Intangible Assets, Net (Excluding Goodwill)	2,422.9		2,412.2
Patents, Licenses And Technology [Member]
Goodwill [Line Items]
Intangible Assets, Gross (Excluding Goodwill)	318.3		309.6
Finite-Lived Intangible Assets, Accumulated Amortization	155.4		144.7
Intangible Assets, Net (Excluding Goodwill)	162.9		164.9
Noncompete Agreements [Member]
Goodwill [Line Items]
Intangible Assets, Gross (Excluding Goodwill)	51.8		51.2
Finite-Lived Intangible Assets, Accumulated Amortization	39.6		37.2
Intangible Assets, Net (Excluding Goodwill)	12.2		14.0
Trade Names [Member]
Goodwill [Line Items]
Intangible Assets, Gross (Excluding Goodwill)	400.5		400.9
Finite-Lived Intangible Assets, Accumulated Amortization	128.7		115.5
Intangible Assets, Net (Excluding Goodwill)	271.8		285.4
Use Rights [Member]
Goodwill [Line Items]
Intangible Assets, Gross (Excluding Goodwill)	6.4		5.5
Finite-Lived Intangible Assets, Accumulated Amortization	0.9		0.6
Intangible Assets, Net (Excluding Goodwill)	5.5		4.9
Canadian licenses [Member]
Goodwill [Line Items]
Intangible Assets, Gross (Excluding Goodwill)	482.6		451.0
Finite-Lived Intangible Assets, Accumulated Amortization	0.0		0.0
Intangible Assets, Net (Excluding Goodwill)	$ 482.6		$ 451.0