GOODWILL AND INTANGIBLE ASSETS (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Jan. 30, 2015	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Senior Notes, Noncurrent						$ 2,900.0
Goodwill	$ 6,389.0		$ 6,389.0		$ 6,166.3		$ 3,099.4
Amortization of intangible assets	41.1	$ 44.9	130.7	$ 120.6
Finite-Lived Intangible Assets, Future Amortization Expense
Estimated amortization expense, 2012	39.2		39.2
Estimated amortization expense, 2013	172.3		172.3
Estimated amortization expense, 2014	159.4		159.4
Estimated amortization expense, 2015	151.9		151.9
Estimated amortization expense, 2016	145.4		145.4
Estimated amortization expense, Thereafter	2,053.8		2,053.8
LabCorp Diagnostics [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill	3,541.9		3,541.9		3,201.7		2,988.9
Covance Drug Development [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 2,847.1		$ 2,847.1		$ 2,964.6		$ 110.5
Senior notes due 2045 [Member]
Finite-Lived Intangible Assets [Line Items]
Senior Notes, Noncurrent						$ 900.0