Period for which ultimate health care cost trend rate is expected to be applicable.

No definition available.

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

- References

No definition available.

+ Details

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

- References

No definition available.

+ Details

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

- Definition

This element represents the number of years over which changes in the fair value of plan assets in the expected return on plan assets line in net periodic (Income)/cost is systematically recognized.

+ References

No definition available.

+ Details

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

- Definition

This element represents percentage of interest rate added to average from August to October of the one-year U.S. Treasury Constant Maturity yield for computation of interest crediting rate.

+ References

No definition available.

+ Details

Name:	ibm_PercentageOfInterestRateAddedToAverageFromAugustToOctoberOfOneYearUSTreasuryConstantMaturityYieldForComputationOfInterestCreditingRate
Namespace Prefix:	ibm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Period of interest rate added to average from August to October.

+ References

No definition available.

+ Details

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

- References

No definition available.

+ Details

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

- Definition

Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation of defined benefit plan.

+ References

+ Details

Name:	us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Weighted average rate increase of compensation, used to determine benefit obligation of defined benefit plan. Plan includes, but is not limited to, pay-related defined benefit plan.

+ References

+ Details

Name:	us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Weighted-average interest crediting rate used to determine benefit obligation of defined benefit plan. Plan includes, but is not limited to, cash balance and other defined benefit plans with promised interest crediting rate.

+ References

+ Details

Name:	us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationWeightedAverageInterestCreditingRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Weighted average rate for present value of future retirement benefits cash flows, used to determine net periodic benefit cost of defined benefit plan.

+ References

+ Details

Name:	us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Weighted average rate of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost of defined benefit plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(3)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e2919-114920

+ Details

Name:	us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Weighted average rate of compensation increase used to determine net periodic benefit cost of defined benefit plan. Plan includes, but is not limited to, pay-related defined benefit plan.

+ References

+ Details

Name:	us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostRateOfCompensationIncrease
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Weighted-average interest crediting rate used to determine net periodic benefit cost of defined benefit plan. Plan includes, but is not limited to, cash balance and other defined benefit plans with promised interest crediting rate.

+ References

+ Details

Name:	us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostWeightedAverageInterestCreditingRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Assumed rate, for next fiscal year, based on annual change in cost of health care cost benefits used to measure expected cost of benefits covered by defined benefit postretirement plan. Factors include, but are not limited to, estimate of health care inflation, change in health care utilization or delivery pattern, technological advances, and change in health status of participant. Excludes factors for change in composition of plan population by age and dependency status.

+ References

+ Details

Name:	us-gaap_DefinedBenefitPlanHealthCareCostTrendRateAssumedNextFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Ultimate trend rate for health care cost for defined benefit postretirement plan.

+ References

+ Details

Name:	us-gaap_DefinedBenefitPlanUltimateHealthCareCostTrendRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- References

No definition available.

+ Details

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

- References

No definition available.

+ Details

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

- Details

Name:	us-gaap_RetirementPlanTypeAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RetirementPlanSponsorLocationAxis=country_US
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementScenarioAxis=srt_ScenarioForecastMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RetirementPlanNameAxis=ibm_PersonalPensionPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RetirementPlanSponsorLocationAxis=us-gaap_ForeignPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RetirementPlanTypeAxis=us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RetirementPlanTypeAxis=us-gaap_DefinedBenefitPostretirementHealthCoverageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Retirement-Related Benefits - Assumptions (Details)	12 Months Ended
Retirement-Related Benefits - Assumptions (Details)	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension Plans
Expected Long-Term Returns on Plan Assets
Period over which changes in fair value of plan assets recognized		5 years
Pension Plans \| U.S.
Weighted-average assumptions used to measure net periodic (income)/cost for the year ended December 31
Discount rate		3.10%	4.10%	3.40%
Expected long-term returns on plan assets		4.50%	5.25%	5.25%
Interest crediting rate		2.70%	3.60%	2.30%
Weighted-average assumptions used to measure benefit obligations at December 31
Discount rate		2.20%	3.10%	4.10%
Interest crediting rate		1.10%	2.70%	3.60%
Pension Plans \| U.S. \| Expected
Weighted-average assumptions used to measure net periodic (income)/cost for the year ended December 31
Expected long-term returns on plan assets	3.75%
Pension Plans \| U.S. \| Personal Pension Plan (PPP)
Interest Crediting Rate
Maturity period of the average interest from August to October		1 year
Percentage interest rate added to average interest from August to October of the one-year U.S. Treasury Constant Maturity yield for computation of interest crediting rate (as a percent)		1.00%
Pension Plans \| Non-U.S.
Weighted-average assumptions used to measure net periodic (income)/cost for the year ended December 31
Discount rate		1.19%	1.85%	1.76%
Expected long-term returns on plan assets		3.37%	4.38%	3.62%
Rate of compensation increase		2.60%	2.18%	2.41%
Interest crediting rate		0.28%	0.30%	0.30%
Weighted-average assumptions used to measure benefit obligations at December 31
Discount rate		0.86%	1.19%	1.85%
Rate of compensation increase		2.50%	2.60%	2.18%
Interest crediting rate		0.26%	0.28%	0.30%
Pension Plans \| Non-U.S. \| Expected
Weighted-average assumptions used to measure net periodic (income)/cost for the year ended December 31
Expected long-term returns on plan assets	2.86%
Nonpension Postretirement Benefit Plans \| U.S.
Weighted-average assumptions used to measure net periodic (income)/cost for the year ended December 31
Discount rate		2.80%	3.90%	3.30%
Interest crediting rate		2.70%	3.60%	2.30%
Weighted-average assumptions used to measure benefit obligations at December 31
Discount rate		1.80%	2.80%	3.90%
Interest crediting rate		1.10%	2.70%	3.60%
Nonpension Postretirement Benefit Plans \| Non-U.S.
Weighted-average assumptions used to measure net periodic (income)/cost for the year ended December 31
Discount rate		4.98%	7.48%	7.28%
Expected long-term returns on plan assets		7.51%	8.64%	8.91%
Weighted-average assumptions used to measure benefit obligations at December 31
Discount rate		4.46%	4.98%	7.48%
Retiree Health Benefits
Healthcare Cost Trend Rate
Health care cost trend rate assumed for next fiscal year		6.25%
Ultimate healthcare cost trend rate		5.00%
Period for ultimate trend rate		6 years