BUSINESS SEGMENT INFORMATION Business Segment Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Segment Reporting Information [Line Items]
Total net revenues	$ 2,295.2	$ 1,772.3
Reimbursement Revenue	72.8	20.9
Revenues	2,368.0	1,793.2
Operating Income (Loss)	301.9	132.4
Earnings before income taxes	256.0	32.5
Provision for income taxes	256.0	32.5
Provision for income taxes	95.5	29.1
Net earnings	160.5	3.4
Net income attributable to Laboratory Corporation of America Holdings	(0.3)	(0.3)
Income Loss from Continuing Operations Before Income Taxes and Minority Interest	(45.9)	(99.9)
Net Income (Loss) Attributable to Parent	160.2	3.1
Corporate Segment [Member]
Segment Reporting Information [Line Items]
Operating Income (Loss)	$ (38.1)	(27.6)
LabCorp Diagnostics [Member]
Segment Reporting Information [Line Items]
Percent of Revenue Contributed	69.30%
Total net revenues	$ 1,590.6	1,472.0
Operating Income (Loss)	$ 277.0	210.4
Covance Drug Development [Member]
Segment Reporting Information [Line Items]
Percent of Revenue Contributed	30.70%
Total net revenues	$ 704.6	300.3
Operating Income (Loss)	$ 63.0	$ (50.4)