Name:	ibm_EmployerContributionAsPercentageOfEligibleCompensationUnderConditionOne
Namespace Prefix:	ibm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Represents the employer's contribution expressed as a percentage of eligible compensation under condition three depending on the employees' eligibility to participate in the PPP as on December 31, 2007.

No definition available.

Name:	ibm_EmployerContributionAsPercentageOfEligibleCompensationUnderConditionThree
Namespace Prefix:	ibm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Represents the employer's contribution expressed as a percentage of eligible compensation under condition two depending on the employees' eligibility to participate in the PPP as on December 31, 2007.

No definition available.

Name:	ibm_EmployerContributionAsPercentageOfEligibleCompensationUnderConditionTwo
Namespace Prefix:	ibm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Minimum amounts that must be invested in company stock.

No definition available.

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

This element represents minimum years of service remaining from retirement eligibility to participate in Future Health Account benefits.

No definition available.

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

The service period after which employees receive automatic contributions and matching contributions.

No definition available.

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

This element represents a number of years used in final pay formula that determines benefits based on salary, years of service, mortality and other participant-specific factors.

No definition available.

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

This element represents maximum percentage of dollar-for-dollar match of employees contribution for those hired after January 1, 2005.

No definition available.

Name:	ibm_PercentageOfEmployeeContributionOnEligibleCompensationForEmployeesHiredPost1stJanuary2005
Namespace Prefix:	ibm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

This element represents maximum percentage of dollar-for-dollar match of employees contribution for those hired prior to January 1, 2005.

No definition available.

Name:	ibm_PercentageOfEmployeeContributionOnEligibleCompensationForEmployeesHiredPrior1stJanuary2005
Namespace Prefix:	ibm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

Name:	ibm_RetirementRelatedDisclosuresLineItems
Namespace Prefix:	ibm_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Employees who were within the specified period of retirement eligibility are covered under the company's prior retiree health benefits arrangements.

No definition available.

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

Name:	ibm_RetirementRelatedBenefitPlansAxis=ibm_PersonalPensionPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	ibm_RetirementRelatedBenefitPlansAxis=ibm_IBM401kPlusPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	ibm_RetirementRelatedBenefitPlansAxis=ibm_IBMExcess401kPlusPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: