Amount of retained interest transferred to a third-party financial institution pursuant to an exchange agreement.

No definition available.

Name:	ibm_AmountOfRetainedInterestTransferred
Namespace Prefix:	ibm_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Ratio applied to the conversion of stock.

+ References

No definition available.

+ Details

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

Numbers shares transferred.

+ References

No definition available.

+ Details

Name:	ibm_InvestmentTransferredShares
Namespace Prefix:	ibm_
Data Type:	xbrli:sharesItemType
Balance Type:	na
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:	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			6 Months Ended
Separation of Kyndryl (Details) $ in Millions	May 23, 2022 shares	May 19, 2022 shares	Jun. 30, 2022 USD ($)	Mar. 31, 2022 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)	Nov. 03, 2021
Discontinued Operations
Numbers shares transferred \| shares		22,300,000
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
Discontinued Operations
Kyndryl stock distributed to IBM stockholders								80.10%
Ownership interest by stockholders (in percent)								19.90%
Amount of retained interest transferred	9.95%
Numbers shares transferred \| shares	22,301,536
Pre-tax gain on sale \| $				$ 68
Managed infrastructure services unit \| Disposed by separation
Discontinued Operations
Separation costs \| $			$ 2		$ 146	$ 5	$ 196