| Cover | Aug. 16, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K/A |
| Document Period End Date | Aug. 16, 2021 |
| Entity Registrant Name | Quest Diagnostics Inc |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-12215 |
| Entity Tax Identification Number | 16-1387862 |
| Entity Address, Address Line One | 500 Plaza Drive |
| Entity Address, City or Town | Secaucus, |
| Entity Address, State or Province | NJ |
| Entity Address, Postal Zip Code | 07094 |
| City Area Code | (973) |
| Local Phone Number | 520-2700 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $0.01 Par Value |
| Trading Symbol | DGX |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001022079 |
| Amendment Flag | true |
| Amendment Description | This Form 8-K/A is being filed as an amendment (“Amendment No. 1”) to the current report on Form 8-K filed by Quest Diagnostics Incorporated (the “Company”) with the Securities and Exchange Commission on August 17, 2021 (the “Original Filing”). The sole purpose of this Amendment No. 1 is to add Inline eXtensible Business Reporting Language (“XBRL”) tagging to the cover page and to furnish Exhibit 104 relating to the same. No other changes have been made to the Original Filing. |
