Name:	ibm_DefinedContributionPensionPlanLiabilitiesNoncurrent
Namespace Prefix:	ibm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The noncurrent portion of the estimated costs associated with on-going workforce reduction actions to improve productivity, cost competitiveness and to rebalance skills. This policy excludes special actions workforce reductions.

No definition available.

Name:	ibm_WorkforceReductionsNoncurrent
Namespace Prefix:	ibm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Carrying value of the obligation (known or estimated) arising from requirements to perform activities to remediate one or more sites, payable after twelve months or beyond the next operating cycle if longer.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 450
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483076/450-20-50-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 410
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481931/410-30-50-7

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 410
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 10
-Subparagraph (d)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481931/410-30-50-10

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.24)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Name:	us-gaap_AccruedEnvironmentalLossContingenciesNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount, after deferred tax asset, of deferred tax liability attributable to taxable differences with jurisdictional netting.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(15)(b)(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479440/944-210-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482525/740-10-45-4

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482525/740-10-45-6

Name:	us-gaap_DeferredIncomeTaxLiabilitiesNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled after one year or the normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483466/210-20-50-3

Name:	us-gaap_DerivativeLiabilitiesNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

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

Amount recognized for uncertainty in income taxes classified as noncurrent.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.24)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Name:	us-gaap_LiabilityForUncertainTaxPositionsNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of liabilities classified as other, due after one year or the normal operating cycle, if longer.

Name:	us-gaap_OtherLiabilitiesNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Obligations not otherwise itemized or categorized in the footnotes to the financial statements that are expected to be paid after one year (or the normal operating cycle, if longer), from the balance sheet date.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(24))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(15))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479853/942-210-S99-1

Name:	us-gaap_OtherSundryLiabilitiesNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Liability for amount due a former employee for benefits as a result of them becoming physically or mentally impaired.

No definition available.