The amount of pension funds allocated to portfolio, which are available for future investments.

No definition available.

Name:	ibm_DefinedBenefitPlanAmountAvailableForFutureInvestments
Namespace Prefix:	ibm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The net increase or decrease in the accumulated plan benefit obligation, during the reporting period, on account of changes in discount rate assumptions.

+ References

No definition available.

+ Details

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

- Definition

The net increase or decrease in the plan benefit obligation, during the reporting period, on account of changes in discount rate assumptions.

+ References

No definition available.

+ Details

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

- Definition

The increase (decrease) in the net periodic income (cost), due to changes in discount rate assumptions.

+ References

No definition available.

+ Details

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

- Definition

The increase (decrease) in net periodic (income) cost due to change in interest crediting rate.

+ References

No definition available.

+ Details

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

- Definition

This element represents the increase (decrease) in healthcare cost trend rate of defined benefit plan assumed over the next three years.

+ References

No definition available.

+ Details

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

- Definition

This element represents the interest crediting rate.

+ References

No definition available.

+ Details

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

- Details

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

- 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

The percentage of board members, elected by employees and retirees for managing investments.

+ References

No definition available.

+ Details

Name:	ibm_PercentageOfBoardMembersElectedByEmployeesAndRetireesForManagingInvestments
Namespace Prefix:	ibm_
Data Type:	num:percentItemType
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

- Details

Name:	us-gaap_DefinedBenefitPlanAssetsTargetAllocationsAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
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- Details

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

- Definition

The interest rate used to adjust for the time value of money for the plan.

+ References

+ Details

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

- Definition

Expected rate of compensation increases (for pay-related plans).

+ References

+ Details

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

- Definition

The interest rate used to adjust for the time value of money.

+ References

+ Details

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

- Definition

An assumption as to the rate of return on plan assets reflecting the average rate of earnings expected on the funds invested or to be invested to provide for the benefits included in the benefit obligation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 30

-Glossary Expected Long-Term Rate of Return on Plan Assets

-URI http://asc.fasb.org/extlink&oid=6512013

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (k)(3)

-URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e1928-114920

+ Details

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

- Definition

Expected rate of compensation increases (for pay-related plans).

+ References

+ Details

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Namespace Prefix:	us-gaap_
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- Definition

Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 30

-Section 35

-Paragraph 50

-URI http://asc.fasb.org/extlink&oid=29635418&loc=d3e12355-114930

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The assumed health care cost trend rate for the next year used to measure the expected cost of benefits covered by the plan (gross eligible charges). This is based upon the annual rate of change in the cost of health care benefits currently provided by the postretirement benefit plan, due to factors other than changes in the composition of the plan population by age and dependency status.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (l)

-URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Health Care Cost Trend Rate

-URI http://asc.fasb.org/extlink&oid=6514820

+ Details

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

- Definition

Target allocation of investments of this type to total plan assets presented on a weighted average basis.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (d)(i)

-URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 5

-Subparagraph (c)(i)

-URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e2446-114920

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Data Type:	num:percentItemType
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- Definition

Percentage of fair value of investments (categorized by debt securities, equity securities, real estate and other plan assets) to the fair value of plan assets held.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 5

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e2446-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (d)(1)

-URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e1928-114920

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Retirement-Related Benefits (Assumptions) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Defined Benefit Pension Plans
Discount Rate
Period over which changes in fair value of plan assets recognized	5 years
U.S. Defined Benefit Pension Plans
Weighted-average assumptions used to measure net periodic (income)/cost for the year ended December 31
Discount rate	3.60%	4.20%	5.00%
Expected long-term returns on plan assets	8.00%	8.00%	8.00%
Weighted-average assumptions used to measure benefit obligations at December 31
Discount rate	4.50%	3.60%	4.20%
Discount Rate
Increase (decrease) in net periodic (income) cost due to change in discount rate	$ (162)	$ (258)	$ (171)
Increase (decrease) in PBO due to change in discount rate	(4,785)	3,414
Investment Policies And Strategies
Fair Value of plan assets	53,954	53,630	51,218
U.S. Defined Benefit Pension Plans \| European Sovereign Debt Investments
Investment Policies And Strategies
Fair Value of plan assets	828
Personal Pension Plan (PPP)
Interest Crediting Rate
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%
Interest crediting rate	1.20%	1.10%	1.30%	1.40%
Increase (decrease) in net periodic income due to change in interest crediting rate	(6)	10	4
Qualified PPP
Investment Policies And Strategies
Fair Value of plan assets	53,954	53,630
Qualified PPP \| Equity securities
Investment Policies And Strategies
Target allocation	42.00%
Qualified PPP \| Fixed income:
Investment Policies And Strategies
Target allocation	47.00%
Qualified PPP \| Real estate
Investment Policies And Strategies
Target allocation	6.00%
Qualified PPP \| Other investments
Investment Policies And Strategies
Target allocation	5.00%
Qualified PPP \| Private equities and private real estate investments
Investment Policies And Strategies
Commitments for future investments in private markets	2,830
Fair Value of plan assets	6,809
Non-U.S. Defined Benefit Pension Plans
Weighted-average assumptions used to measure net periodic (income)/cost for the year ended December 31
Discount rate	3.23%	4.28%	4.33%
Expected long-term returns on plan assets	6.21%	6.26%	6.41%
Rate of compensation increase	2.51%	2.43%	2.37%
Weighted-average assumptions used to measure benefit obligations at December 31
Discount rate	3.32%	3.23%	4.28%
Rate of compensation increase	2.52%	2.51%	2.43%
Investment Policies And Strategies
Fair Value of plan assets	39,464	38,058	35,362
Non-U.S. Defined Benefit Pension Plans \| Maximum
Investment Policies And Strategies
Percentage of board members, elected by employees and retirees for managing investments (as a percent)	50.00%
Non-U.S. Defined Benefit Pension Plans \| Equity securities
Investment Policies And Strategies
Target allocation	33.00%
Non-U.S. Defined Benefit Pension Plans \| Fixed income:
Investment Policies And Strategies
Target allocation	54.00%
Non-U.S. Defined Benefit Pension Plans \| European Sovereign Debt Investments
Investment Policies And Strategies
Fair Value of plan assets	11,000
Non-U.S. Defined Benefit Pension Plans \| European Sovereign Debt Investments \| Italy Spain and Ireland \| Maximum
Investment Policies And Strategies
Fair value of plan assets as percent of total non-US plan assets	1.00%
Non-U.S. Defined Benefit Pension Plans \| Real estate
Investment Policies And Strategies
Target allocation	2.00%
Non-U.S. Defined Benefit Pension Plans \| Other investments
Investment Policies And Strategies
Target allocation	11.00%
Nonpension Postretirement Plans
Discount Rate
Increase (decrease) in net periodic (income) cost due to change in discount rate	0	0	0
Increase (decrease) in APBO due to changes in discount rate	(298)	252
Healthcare Cost Trend Rate
Health care cost trend rate assumed for next fiscal year	6.50%
Health care cost trend rate assumed over the next three years	5.00%
U.S. Nonpension Postretirement Benefit Plans
Weighted-average assumptions used to measure net periodic (income)/cost for the year ended December 31
Discount rate	3.30%	3.90%	4.80%
Expected long-term returns on plan assets	0.35%
Weighted-average assumptions used to measure benefit obligations at December 31
Discount rate	4.10%	3.30%	3.90%
Investment Policies And Strategies
Fair Value of plan assets	177	433	38
Non-U.S. Nonpension Postretirement Plans
Weighted-average assumptions used to measure net periodic (income)/cost for the year ended December 31
Discount rate	6.43%	7.37%	7.75%
Expected long-term returns on plan assets	9.01%	9.01%	9.07%
Weighted-average assumptions used to measure benefit obligations at December 31
Discount rate	7.78%	6.43%	7.37%
Investment Policies And Strategies
Fair Value of plan assets	$ 92	$ 119	$ 112