BUSINESS SEGMENT INFORMATION Business Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Segment Reporting Information [Line Items]
Total net revenues	$ 1,516.4	$ 1,468.2	$ 2,947.1	$ 2,909.1
Total operating income	246.7	269.3	450.0	531.3
Non-operating expenses, net	14.2	19.3	29.8	39.9
Earnings before income taxes	232.5	250.0	420.2	491.4
Provision for income taxes	90.8	97.7	165.0	191.4
Net earnings	141.7	152.3	255.2	300.0
Less income attributable to noncontrolling interests	(0.4)	(0.4)	(0.8)	(0.8)
Net income attributable to Laboratory Corporation of America Holdings	141.3	151.9	254.4	299.2
Clinical diagnostics laboratory [Member]
Segment Reporting Information [Line Items]
Total net revenues	1,431.3	1,381.6	2,781.6	2,735.6
Total operating income	375.8	380.1	706.7	754.3
General corporate expenses [Member]
Segment Reporting Information [Line Items]
Total operating income	(151.9)	(134.0)	(300.1)	(270.7)
Other Segments [Member]
Segment Reporting Information [Line Items]
Total net revenues	85.1	86.6	165.5	173.5
Total operating income	$ 22.8	$ 23.2	$ 43.4	$ 47.7