QUARTERLY DATA (UNAUDITED) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Summary of unaudited quarterly data
Net sales	$ 1,437.0	$ 1,462.2	$ 1,468.2	$ 1,440.9	$ 1,405.3	$ 1,419.4	$ 1,423.4	$ 1,423.3	$ 5,808.3	$ 5,671.4	$ 5,542.3
Gross profit	526.1	547.6	577.3	572.2	538.0	556.1	579.5	576.1	2,223.2	2,249.7	2,274.7
Net earnings attributable to Laboratory Corporation of America Holdings	$ 126.4	$ 148.3	$ 151.9	$ 147.2	$ 120.2	$ 148.0	$ 153.3	$ 161.6	$ 573.8	$ 583.1	$ 519.7
Earnings Per Share
Basic earnings per share (in dollars per share)	$ 1.46	$ 1.66	$ 1.65	$ 1.58	$ 1.28	$ 1.56	$ 1.59	$ 1.66	$ 6.36	$ 6.09	$ 5.20
Diluted earnings per common share (in dollars per share)	$ 1.43	$ 1.63	$ 1.62	$ 1.56	$ 1.26	$ 1.53	$ 1.56	$ 1.63	$ 6.25	$ 5.99	$ 5.11