Document and Entity Information Document - USD ($) shares in Millions, $ in Millions	3 Months Ended									12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Feb. 22, 2017
Entity Information [Line Items]
Net sales	$ 2,387.3	$ 2,372.7	$ 2,382.0	$ 2,295.2	$ 2,244.8	$ 2,269.9	$ 2,218.7	$ 1,772.3	$ 6,011.6	$ 9,437.2	$ 8,505.7
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, 2016
Document Fiscal Year Focus										2016
Document Fiscal Period Focus										FY
Amendment Flag										false
Entity Common Stock, Shares Outstanding													102.3
Entity Well-known Seasoned Issuer										Yes
Entity Voluntary Filers										No
Entity Current Reporting Status										Yes
Entity Public Float			$ 12,700.0
Genomic and Esoteric Testing [Member]
Entity Information [Line Items]
Net sales											$ 2,306.4	$ 173.6