| Document and Entity Information | Oct. 29, 2020 |
| Cover [Abstract] | |
| Document Period End Date | Oct. 29, 2020 |
| Entity Registrant Name | UNISYS CORP |
| Amendment Flag | false |
| Entity Central Index Key | 0000746838 |
| Document Type | 8-K |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 1-8729 |
| Entity Tax Identification Number | 38-0387840 |
| Entity Address, Address Line One | 801 Lakeview Drive |
| Entity Address, Address Line Two | 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 |
| Security 12b Title | Common Stock, par value $.01 |
| Trading Symbol | UIS |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
