| Cover Page | Jan. 26, 2023 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Jan. 26, 2023 |
| Entity Registrant Name | Robert Half International Inc. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 01-10427 |
| Entity Central Index Key | 0000315213 |
| Amendment Flag | false |
| Entity Tax Identification Number | 94-1648752 |
| Entity Address, Address Line One | 2884 Sand Hill Road, Suite 200, |
| Entity Address, City or Town | Menlo Park, |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 94025 |
| City Area Code | 650 |
| Local Phone Number | 234-6000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, Par Value $.001 per Share |
| Trading Symbol | RHI |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
