| Cover page Cover page | Nov. 02, 2020 |
| Cover page. [Abstract] | |
| Written Communications | false |
| Entity Address, Address Line One | 358 South Main Street |
| Entity Tax Identification Number | 13-3757370 |
| Entity Central Index Key | 0000920148 |
| Document Period End Date | Nov. 2, 2020 |
| Entity Registrant Name | LABORATORY CORPORATION OF AMERICA HOLDINGS |
| 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 Emerging Growth Company | false |
| Amendment Flag | false |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 1-11353 |
| Entity Address, City or Town | Burlington, |
| Entity Address, State or Province | NC |
| Entity Address, Postal Zip Code | 27215 |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Document Type | 8-K/A |
