Ratio applied to the conversion of stock.

No definition available.

Name:	ibm_ConversionOfStockRatio
Namespace Prefix:	ibm_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of estimated obligations for services to be rendered by the company to new company.

+ References

No definition available.

+ Details

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

- Definition

The amount of separation costs of discontinued operations.

+ References

No definition available.

+ Details

Name:	ibm_DisposalGroupIncludingDiscontinuedOperationsSeparationCosts
Namespace Prefix:	ibm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The period in which the transition services to be given by the company after separation.

+ References

No definition available.

+ Details

Name:	ibm_DisposalGroupIncludingDiscontinuedOperationsTransitionServicesPeriod
Namespace Prefix:	ibm_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The period in which the upgraded hardware to be provided by the company after separation.

+ References

No definition available.

+ Details

Name:	ibm_DisposalGroupIncludingDiscontinuedOperationsUpgradedHardwareServicesPeriod
Namespace Prefix:	ibm_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of gain loss on sale of interest in joint venture.

+ References

No definition available.

+ Details

Name:	ibm_GainLossOnSaleOfInterestInJointVenture
Namespace Prefix:	ibm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the percentage of Kyndryl publicly traded common stock distributed to IBM stockholders of record as of 10/25/2021

+ References

No definition available.

+ Details

Name:	ibm_PercentageOfKyndrylStockDistributionToIbmStockholders
Namespace Prefix:	ibm_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

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

- Definition

The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

+ References

No definition available.

+ Details

Name:	us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	dei_LegalEntityAxis=ibm_KyndrylHoldingsIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BalanceSheetLocationAxis=ibm_AccruedLiabilitiesAndOtherLiabilitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_OwnershipAxis=ibm_KyndrylHoldingsIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=ibm_ManagedInfrastructureServicesUnitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DisposalGroupClassificationAxis=us-gaap_DiscontinuedOperationsDisposedOfByMeansOtherThanSaleSpinoffMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Separation of Kyndryl (Details) $ in Millions	3 Months Ended
Separation of Kyndryl (Details) $ in Millions	Mar. 31, 2022 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2021 USD ($)	Nov. 03, 2021
Kyndryl Holdings, Inc
Discontinued Operations
Kyndryl stock distributed to IBM stockholders				80.10%
Share conversion ratio				0.2
Upgraded hardware period	2 years
Kyndryl Holdings, Inc \| Maximum
Discontinued Operations
Transition services period	2 years
Kyndryl Holdings, Inc \| Accrued expenses and other liabilities
Discontinued Operations
Estimated obligation	$ 265		$ 265
Kyndryl Holdings, Inc
Discontinued Operations
Kyndryl stock distributed to IBM stockholders				80.10%
Ownership interest by stockholders (in percent)				19.90%
Pre-tax gain on sale	68
Managed infrastructure services unit \| Disposed by separation
Discontinued Operations
Separation costs	$ 3	$ 50