Document and Entity Information Document - shares shares in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2017	Jul. 28, 2017
Document Information [Line Items]
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-Q
Document Period End Date		Jun. 30, 2017
Document Fiscal Year Focus		2017
Document Fiscal Period Focus		Q2
Amendment Flag		false
Entity Common Stock, Shares Outstanding			101.8
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes