Document and Entity Information Document - USD ($) shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Feb. 23, 2016
Entity Information [Line Items]
Net sales	$ 2,244.8	$ 2,269.9	$ 2,218.7	$ 1,772.3	$ 1,512.7	$ 1,551.8	$ 1,516.4	$ 1,430.7	$ 8,505.7	$ 6,011.6	$ 5,808.3
Entity Registrant Name									LABORATORY CORP OF AMERICA HOLDINGS
Entity Central Index Key									0000920148
Current Fiscal Year End Date									--12-31
Entity Filer Category									Large Accelerated Filer
Document Type									10-K
Document Period End Date									Dec. 31, 2015
Document Fiscal Year Focus									2015
Document Fiscal Period Focus									FY
Amendment Flag									false
Entity Common Stock, Shares Outstanding												101.7
Entity Well-known Seasoned Issuer									Yes
Entity Voluntary Filers									No
Entity Current Reporting Status									Yes
Entity Public Float			$ 12,100.0
Genomic and Esoteric Testing [Member]
Entity Information [Line Items]
Net sales										$ 173.6	$ 138.9