| Cover | Jun. 15, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Jun. 15, 2021 |
| Entity Registrant Name | UNISYS CORP |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 1-8729 |
| Entity Tax Identification Number | 38-0387840 |
| Entity Address, Address Line One | 801 Lakeview Drive, Suite 100 |
| Entity Address, City or Town | Blue Bell, |
| Entity Address, State or Province | PA |
| Entity Address, Postal Zip Code | 19422 |
| City Area Code | 215 |
| Local Phone Number | 986-4011 |
| 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 $.01 |
| Trading Symbol | UIS |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0000746838 |
| Amendment Flag | false |
