| Cover Page Cover Page | Oct. 27, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Oct. 27, 2021 |
| Entity Registrant Name | UNITED RENTALS, INC. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-14387 |
| Entity Tax Identification Number | 06-1522496 |
| Entity Address, Address Line One | 100 First Stamford Place, Suite 700 |
| Entity Address, City or Town | Stamford |
| Entity Address, State or Province | CT |
| Entity Address, Postal Zip Code | 06902 |
| City Area Code | 203 |
| Local Phone Number | 622-3131 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $.01 par value, of United Rentals, Inc. |
| Trading Symbol | URI |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001067701 |
| Amendment Flag | false |
