Cover Page - shares shares in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020	Oct. 28, 2020
Document Information [Table]
Entity Interactive Data Current		Yes
Entity Filer Category		Large Accelerated Filer
Entity Small Business		false
Entity Emerging Growth Company		false
Entity Shell Company		false
Entity Common Stock, Shares Outstanding			97.4
Document Fiscal Period Focus	Q3
Amendment Flag	false
Document Type		10-Q
Document Quarterly Report		true
Document Period End Date	Sep. 30, 2020
Document Transition Report		false
Entity File Number		1-11353
Entity Registrant Name		LABORATORY CORPORATION OF AMERICA HOLDINGS
Entity Incorporation, State or Country Code		DE
Entity Tax Identification Number		13-3757370
Entity Address, Address Line One		358 South Main Street
Entity Address, City or Town		Burlington,
Entity Address, State or Province		NC
Entity Address, Postal Zip Code		27215
City Area Code		336
Local Phone Number		229-1127
Title of 12(b) Security		Common Stock, $0.10 par value
Trading Symbol		LH
Security Exchange Name		NYSE
Entity Current Reporting Status		Yes
Document Fiscal Year Focus	2020
Current Fiscal Year End Date	--12-31
Entity Central Index Key	0000920148