BUSINESS SEGMENT INFORMATION Business Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Segment Reporting Information [Line Items]
Total net revenues	$ 1,430.7	$ 1,440.9
Total operating income	203.3	262.0
Non-operating expenses, net	(15.6)	(20.6)
Earnings before income taxes	187.7	241.4
Provision for income taxes	74.2	93.8
Net earnings	113.5	147.6
Less income attributable to noncontrolling interests	(0.4)	(0.4)
Net income attributable to Laboratory Corporation of America Holdings	113.1	147.2
Clinical diagnostics laboratory [Member]
Segment Reporting Information [Line Items]
Total net revenues	1,350.3	1,354.0
Total operating income	330.9	374.2
General corporate expenses [Member]
Segment Reporting Information [Line Items]
Total operating income	(148.2)	(136.7)
Other Segments [Member]
Segment Reporting Information [Line Items]
Total net revenues	80.4	86.9
Total operating income	$ 20.6	$ 24.5