Income taxes - Tax Loss Carryforwards (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
U.S. Federal	$ 378.6
State and local	178.0
Foreign	268.9
Total tax loss carryforwards	825.5	$ 840.4
Operating Loss Carryforwards [Line Items]
Tax loss carryforwards, not set to expire	275.3
Total tax loss carryforwards	825.5	$ 840.4
2023
Operating Loss Carryforwards [Line Items]
Tax loss carryforwards, set to expire	13.2
2024
Operating Loss Carryforwards [Line Items]
Tax loss carryforwards, set to expire	12.7
2025
Operating Loss Carryforwards [Line Items]
Tax loss carryforwards, set to expire	19.5
2026
Operating Loss Carryforwards [Line Items]
Tax loss carryforwards, set to expire	10.7
2027
Operating Loss Carryforwards [Line Items]
Tax loss carryforwards, set to expire	59.9
Thereafter
Operating Loss Carryforwards [Line Items]
Tax loss carryforwards, set to expire	$ 434.2

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 8
-URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32632-109319

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 6
-URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32621-109319

+ Details

Name:	us-gaap_DeferredTaxAssetsOperatingLossCarryforwards
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible domestic operating loss carryforwards. Excludes state and local operating loss carryforwards.

+ References

+ Details

Name:	us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsDomestic
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible foreign operating loss carryforwards.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 6
-URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32621-109319

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 8
-URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32632-109319

+ Details

Name:	us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsForeign
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards that are not subject to expiration dates.

+ References

No definition available.

+ Details

Name:	us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible state and local operating loss carryforwards.

+ References

+ Details

Name:	us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards that are subject to expiration dates.

+ References

No definition available.

+ Details

Name:	us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_IncomeTaxDisclosureAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_OperatingLossCarryforwardsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	uis_PeriodAxis=uis_TaxLossCreditCarryForwardsYearOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	uis_PeriodAxis=uis_TaxLossCreditCarryForwardsYearTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	uis_PeriodAxis=uis_TaxLossCreditCarryForwardsYearThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	uis_PeriodAxis=uis_TaxLossCreditCarryForwardsYearFourMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	uis_PeriodAxis=uis_TaxLossCreditCarryForwardsYearFiveMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	uis_PeriodAxis=uis_TaxCreditLossCarryForwardsThereafterMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: