Name:	ibm_LossContingencyDirectDamagesAwardedAndAppealed
Namespace Prefix:	ibm_
Data Type:	xbrli:monetaryItemType
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The value (monetary amount) of the punitive damages awarded to the plaintiff which were subsequently appealed in the course of a legal matter.

No definition available.

Name:	ibm_LossContingencyPunitiveDamagesAwardedAndAppealed
Namespace Prefix:	ibm_
Data Type:	xbrli:monetaryItemType
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Period Type:	duration

The number of former executives of the reporting entity named as defendants.

No definition available.

Name:	ibm_NumberOfFormerExecutivesNamedAsDefendants
Namespace Prefix:	ibm_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

the number of officers or executives of the reporting entity named as defendants.

No definition available.

Name:	ibm_NumberOfOfficerOrExecutivesNamedAsDefendants
Namespace Prefix:	ibm_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

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
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
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The value (monetary amount) of the award the plaintiff seeks in the legal matter.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=121557415&loc=d3e14435-108349

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=121557415&loc=d3e14557-108349

Name:	us-gaap_LossContingencyDamagesSoughtValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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The total number of new claims filed pertaining to a loss contingency during the period.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
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Period Type:	duration

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

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Namespace Prefix:
Data Type:	na
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Name:	srt_LitigationCaseAxis=ibm_BmcV.IbmMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_LitigationCaseAxis=ibm_LitigationCaseInUnitedStatesDistrictCourtRegardingPutativeSecuritiesClassActionMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	srt_RangeAxis=srt_MinimumMember
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