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Represents the period for which reports need to be submitted to Securities Exchange Commission and court on certain matters, including those relating to compliance with the Foreign Corrupt Practices Act of 1977.

No definition available.

Name:	ibm_LossContingencyPeriodForWhichReportsAreToBeSubmittedToSecuritiesExchangeCommissionAndCourt
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Number of representative beneficiaries of the UK Trust membership against which the entity initiated legal proceedings.

No definition available.

Name:	ibm_NumberOfRepresentativeBeneficiariesOfTrustMembership
Namespace Prefix:	ibm_
Data Type:	xbrli:integerItemType
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Amount of judgment or settlement awarded to (against) the entity in respect of litigation.

No definition available.

Name:	us-gaap_LitigationSettlementAmount
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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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.

No definition available.

Name:	us-gaap_LossContingenciesLineItems
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Data Type:	xbrli:stringItemType
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Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14435-108349

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 9
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14557-108349

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Data Type:	xbrli:monetaryItemType
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Number of defendants named in a legal action.

No definition available.

Name:	us-gaap_LossContingencyNumberOfDefendants
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Data Type:	xbrli:integerItemType
Balance Type:	na
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Number of pending claims pertaining to a loss contingency.

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Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

The number of countries in which the entity operates as of balance sheet date.

No definition available.

Name:	us-gaap_NumberOfCountriesInWhichEntityOperates
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Name:	us-gaap_IncomeTaxAuthorityAxis=us-gaap_ForeignCountryMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	us-gaap_StatementGeographicalAxis=country_BR
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	us-gaap_LitigationCaseAxis=ibm_LitigationCaseInunitedStatesDistrictCourtRegardingDivestingMicroelectronicsBusinessMember
Namespace Prefix:
Data Type:	na
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Period Type:

Name:	us-gaap_LitigationCaseAxis=ibm_LitigationCaseRelatedToViolationsOfEmployeeRetirementIncomeSecurityActInunitedStatesDistrictCourtRegardingDivestingMicroelectronicsBusinessMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	dei_LegalEntityAxis=ibm_IBMUnitedKingdomLimitedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_LitigationCaseAxis=ibm_LitigationRelatedToDefinedBenefitPlansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=ibm_IBMUKPensionsTrustMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=ibm_CivilEnforcementActionWithSECMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=ibm_StateOfIndianaMember
Namespace Prefix:
Data Type:	na
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