Litigation and contingencies - Summary (Details) $ in Millions	Dec. 31, 2021 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Amount related to unreserved tax-related matters, inclusive of interest (up to)	$ 75

Unreserved Tax Related Matters Inclusive of Interest

No definition available.

Name:	uis_UnreservedTaxRelatedMattersInclusiveOfInterest
Namespace Prefix:	uis_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant