The period of time for the trial.

No definition available.

Name:	ibm_DurationOfTrial
Namespace Prefix:	ibm_
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Period Type:	duration

- Definition

the number of officers or executives of the reporting entity named as defendants.

+ References

No definition available.

+ Details

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Namespace Prefix:	ibm_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of representative beneficiaries of the UK Trust membership against which the entity initiated legal proceedings.

+ References

No definition available.

+ Details

Name:	ibm_NumberOfRepresentativeBeneficiariesOfTrustMembership
Namespace Prefix:	ibm_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of judgment or settlement awarded to (against) the entity in respect of litigation.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- 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

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Data Type:	xbrli:stringItemType
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Period Type:	duration

- Definition

The value (monetary amount) of the award the plaintiff seeks in the legal matter.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14557-108349

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14435-108349

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

- Definition

Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14435-108349

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 9
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14557-108349

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Number of pending claims pertaining to a loss contingency.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of countries in which the entity operates as of balance sheet date.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LitigationCaseAxis=ibm_LitigationCaseRelatedToViolationsOfEmployeeRetirementIncomeSecurityActInUnitedStatesDistrictCourtRegardingDivestingMicroelectronicsBusinessMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Contingencies (Details) $ in Millions			1 Months Ended		3 Months Ended
Contingencies (Details) $ in Millions	Feb. 13, 2014 USD ($)	Jul. 18, 2012 USD ($)	May 31, 2015 defendant	May 31, 2010 defendant	Mar. 31, 2017 USD ($) country claim
IBM v. State Of Indiana
Loss Contingencies
Duration of trial		42 days
Amount of settlement to be (paid)/received	$ 50	$ 52
IBM United Kingdom Limited vs. IBM UK Pension Trusts
Loss Contingencies
Number of representative beneficiaries of the UK Trust membership \| defendant				2
Loss contingency, estimate of possible loss					$ 290
Individual Participants Of Defined Benefit Plans vs. IBM United Kingdom
Loss Contingencies
Claims pending \| claim					290
Litigation Case In United States District Court regarding divesting Microelectronics business, alleging violations of the Employee Retirement Income Security Act
Loss Contingencies
Number of officers or executives named as defendants \| defendant			3
Brazil Tax Matters
Loss Contingencies
Damages sought, value					$ 1,000
Minimum
Loss Contingencies
Clients' presence in number of countries \| country					175