GOODWILL AND INTANGIBLE ASSETS (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Feb. 19, 2015	Jan. 30, 2015	Dec. 31, 2014	Dec. 31, 2013
Finite-Lived Intangible Assets [Line Items]
Senior Notes, Noncurrent						$ 2,900.0
Goodwill	$ 6,068.6		$ 6,068.6				$ 3,099.4	$ 3,022.8
Amortization of intangible assets	47.1	$ 18.3	126.2	$ 61.3
Finite-Lived Intangible Assets, Future Amortization Expense
Estimated amortization expense, 2012		47.9		47.9
Estimated amortization expense, 2013		183.3		183.3
Estimated amortization expense, 2014		176.1		176.1
Estimated amortization expense, 2015		165.4		165.4
Estimated amortization expense, 2016		158.7		158.7
Estimated amortization expense, Thereafter		$ 2,259.9		$ 2,259.9
LabCorp Diagnostics [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 3,050.2		$ 3,050.2				2,988.9
Other Segments [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill							$ 110.5
Covance [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill					$ 2,907.8
Senior notes due 2045 [Member]
Finite-Lived Intangible Assets [Line Items]
Senior Notes, Noncurrent						$ 900.0