GOODWILL AND INTANGIBLE ASSETS (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015	Jan. 30, 2015	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Senior Notes, Noncurrent						$ 2,900.0
Goodwill	$ 6,218.3		$ 6,218.3		$ 6,191.9		$ 3,099.4
Amortization of intangible assets	45.3	$ 44.6	89.6	$ 75.7
Finite-Lived Intangible Assets, Future Amortization Expense
Estimated amortization expense, 2012	82.7		82.7
Estimated amortization expense, 2013	172.0		172.0
Estimated amortization expense, 2014	161.3		161.3
Estimated amortization expense, 2015	154.4		154.4
Estimated amortization expense, 2016	148.0		148.0
Estimated amortization expense, Thereafter	2,087.0		2,087.0
LabCorp Diagnostics [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill	3,338.2		3,338.2		3,201.7		2,988.9
Covance Drug Development [Member]
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 2,880.1		$ 2,880.1		$ 2,990.2		$ 110.5
Senior notes due 2045 [Member]
Finite-Lived Intangible Assets [Line Items]
Senior Notes, Noncurrent						$ 900.0