Document and Entity Information	Jul. 20, 2020
Document Information [Line Items]
Document Type	8-K
Document Period End Date	Jul. 20, 2020
Entity File Number	1-2360
Entity Registrant Name	INTERNATIONAL BUSINESS MACHINES CORPORATION
Entity Incorporation, State or Country Code	NY
Entity Tax Identification Number	13-0871985
Entity Address, Address Line One	One New Orchard Road
Entity Address, City or Town	Armonk
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10504
City Area Code	914
Local Phone Number	499-1900
Written Communications	false
Soliciting Material	false
Pre-commencement Tender Offer	false
Pre-commencement Issuer Tender Offer	false
Entity Emerging Growth Company	false
Entity Central Index Key	0000051143
Amendment Flag	false
New York Stock Exchange \| Common Stock
Document Information [Line Items]
Title of 12(b) Security	Capital stock, par value $.20 per share
Trading Symbol	IBM
Security Exchange Name	NYSE
New York Stock Exchange \| 2.750% Notes due 2020
Document Information [Line Items]
Title of 12(b) Security	2.750% Notes due 2020
Trading Symbol	IBM 20B
Security Exchange Name	NYSE
New York Stock Exchange \| 1.875% Notes due 2020
Document Information [Line Items]
Title of 12(b) Security	1.875% Notes due 2020
Trading Symbol	IBM 20A
Security Exchange Name	NYSE
New York Stock Exchange \| 0.500% Notes due 2021
Document Information [Line Items]
Title of 12(b) Security	0.500% Notes due 2021
Trading Symbol	IBM 21B
Security Exchange Name	NYSE
New York Stock Exchange \| 2.625% Notes due 2022
Document Information [Line Items]
Title of 12(b) Security	2.625% Notes due 2022
Trading Symbol	IBM 22A
Security Exchange Name	NYSE
New York Stock Exchange \| 1.250% Notes due 2023
Document Information [Line Items]
Title of 12(b) Security	1.250% Notes due 2023
Trading Symbol	IBM 23A
Security Exchange Name	NYSE
New York Stock Exchange \| 0.375% Notes due 2023
Document Information [Line Items]
Title of 12(b) Security	0.375% Notes due 2023
Trading Symbol	IBM 23B
Security Exchange Name	NYSE
New York Stock Exchange \| 1.125% Notes due 2024
Document Information [Line Items]
Title of 12(b) Security	1.125% Notes due 2024
Trading Symbol	IBM 24A
Security Exchange Name	NYSE
New York Stock Exchange \| 2.875% Notes due 2025
Document Information [Line Items]
Title of 12(b) Security	2.875% Notes due 2025
Trading Symbol	IBM 25A
Security Exchange Name	NYSE
New York Stock Exchange \| 0.950% Notes due 2025
Document Information [Line Items]
Title of 12(b) Security	0.950% Notes due 2025
Trading Symbol	IBM 25B
Security Exchange Name	NYSE
New York Stock Exchange \| 0.875% Notes due 2025
Document Information [Line Items]
Title of 12(b) Security	0.875% Notes due 2025
Trading Symbol	IBM 25C
Security Exchange Name	NYSE
New York Stock Exchange \| 0.300% Notes due 2026
Document Information [Line Items]
Title of 12(b) Security	0.300% Notes due 2026
Trading Symbol	IBM 26B
Security Exchange Name	NYSE
New York Stock Exchange \| 1.250% Notes due 2027
Document Information [Line Items]
Title of 12(b) Security	1.250% Notes due 2027
Trading Symbol	IBM 27B
Security Exchange Name	NYSE
New York Stock Exchange \| 1.750% Notes due 2028
Document Information [Line Items]
Title of 12(b) Security	1.750% Notes due 2028
Trading Symbol	IBM 28A
Security Exchange Name	NYSE
New York Stock Exchange \| 0.300% Notes due 2028
Document Information [Line Items]
Title of 12(b) Security	0.300% Notes due 2028
Trading Symbol	IBM 28B
Security Exchange Name	NYSE
New York Stock Exchange \| 1.500% Notes due 2029
Document Information [Line Items]
Title of 12(b) Security	1.500% Notes due 2029
Trading Symbol	IBM 29
Security Exchange Name	NYSE
New York Stock Exchange \| 1.750% Notes due 2031
Document Information [Line Items]
Title of 12(b) Security	1.750% Notes due 2031
Trading Symbol	IBM 31
Security Exchange Name	NYSE
New York Stock Exchange \| 0.650% Notes due 2032
Document Information [Line Items]
Title of 12(b) Security	0.650% Notes due 2032
Trading Symbol	IBM 32A
Security Exchange Name	NYSE
New York Stock Exchange \| 1.200% Notes due 2040
Document Information [Line Items]
Title of 12(b) Security	1.200% Notes due 2040
Trading Symbol	IBM 40
Security Exchange Name	NYSE
New York Stock Exchange \| 7.00% Debentures due 2025
Document Information [Line Items]
Title of 12(b) Security	7.00% Debentures due 2025
Trading Symbol	IBM 25
Security Exchange Name	NYSE
New York Stock Exchange \| 6.22% Debentures due 2027
Document Information [Line Items]
Title of 12(b) Security	6.22% Debentures due 2027
Trading Symbol	IBM 27
Security Exchange Name	NYSE
New York Stock Exchange \| 6.50% Debentures due 2028
Document Information [Line Items]
Title of 12(b) Security	6.50% Debentures due 2028
Trading Symbol	IBM 28
Security Exchange Name	NYSE
New York Stock Exchange \| 7.00% Debentures due 2045
Document Information [Line Items]
Title of 12(b) Security	7.00% Debentures due 2045
Trading Symbol	IBM 45
Security Exchange Name	NYSE
New York Stock Exchange \| 7.125% Debentures due 2096
Document Information [Line Items]
Title of 12(b) Security	7.125% Debentures due 2096
Trading Symbol	IBM 96
Security Exchange Name	NYSE
Chicago Stock Exchange \| Common Stock
Document Information [Line Items]
Title of 12(b) Security	Capital stock, par value $.20 per share
Trading Symbol	IBM
Security Exchange Name	CHX

Boolean flag that is true when the XBRL content amends previously-filed or accepted submission.

No definition available.

Name:	dei_AmendmentFlag
Namespace Prefix:	dei_
Data Type:	xbrli:booleanItemType
Balance Type:	na
Period Type:	duration

- Definition

Area code of city

+ References

No definition available.

+ Details

Name:	dei_CityAreaCode
Namespace Prefix:	dei_
Data Type:	xbrli:normalizedStringItemType
Balance Type:	na
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

Name:	dei_DocumentInformationLineItems
Namespace Prefix:	dei_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The end date of the period reflected on the cover page if a periodic report. For all other reports and registration statements containing historical data, it is the date up through which that historical data is presented. If there is no historical data in the report, use the filing date. The format of the date is YYYY-MM-DD.

+ References

No definition available.

+ Details

Name:	dei_DocumentPeriodEndDate
Namespace Prefix:	dei_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

The type of document being provided (such as 10-K, 10-Q, 485BPOS, etc). The document type is limited to the same value as the supporting SEC submission type, or the word 'Other'.

+ References

No definition available.

+ Details

Name:	dei_DocumentType
Namespace Prefix:	dei_
Data Type:	dei:submissionTypeItemType
Balance Type:	na
Period Type:	duration

- Definition

Address Line 1 such as Attn, Building Name, Street Name

+ References

No definition available.

+ Details

Name:	dei_EntityAddressAddressLine1
Namespace Prefix:	dei_
Data Type:	xbrli:normalizedStringItemType
Balance Type:	na
Period Type:	duration

- Definition

Name of the City or Town

+ References

No definition available.

+ Details

Name:	dei_EntityAddressCityOrTown
Namespace Prefix:	dei_
Data Type:	xbrli:normalizedStringItemType
Balance Type:	na
Period Type:	duration

- Definition

Code for the postal or zip code

+ References

No definition available.

+ Details

Name:	dei_EntityAddressPostalZipCode
Namespace Prefix:	dei_
Data Type:	xbrli:normalizedStringItemType
Balance Type:	na
Period Type:	duration

- Definition

Name of the state or province.

+ References

No definition available.

+ Details

Name:	dei_EntityAddressStateOrProvince
Namespace Prefix:	dei_
Data Type:	dei:stateOrProvinceItemType
Balance Type:	na
Period Type:	duration

- Definition

A unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation 12B
-Number 240
-Section 12
-Subsection b-2

+ Details

Name:	dei_EntityCentralIndexKey
Namespace Prefix:	dei_
Data Type:	dei:centralIndexKeyItemType
Balance Type:	na
Period Type:	duration

- Definition

Indicate if registrant meets the emerging growth company criteria.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation 12B
-Number 240
-Section 12
-Subsection b-2

+ Details

Name:	dei_EntityEmergingGrowthCompany
Namespace Prefix:	dei_
Data Type:	xbrli:booleanItemType
Balance Type:	na
Period Type:	duration

- Definition

Commission file number. The field allows up to 17 characters. The prefix may contain 1-3 digits, the sequence number may contain 1-8 digits, the optional suffix may contain 1-4 characters, and the fields are separated with a hyphen.

+ References

No definition available.

+ Details

Name:	dei_EntityFileNumber
Namespace Prefix:	dei_
Data Type:	dei:fileNumberItemType
Balance Type:	na
Period Type:	duration

- Definition

Two-character EDGAR code representing the state or country of incorporation.

+ References

No definition available.

+ Details

Name:	dei_EntityIncorporationStateCountryCode
Namespace Prefix:	dei_
Data Type:	dei:edgarStateCountryItemType
Balance Type:	na
Period Type:	duration

- Definition

The exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation 12B
-Number 240
-Section 12
-Subsection b-2

+ Details

Name:	dei_EntityRegistrantName
Namespace Prefix:	dei_
Data Type:	xbrli:normalizedStringItemType
Balance Type:	na
Period Type:	duration

- Definition

The Tax Identification Number (TIN), also known as an Employer Identification Number (EIN), is a unique 9-digit value assigned by the IRS.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation 12B
-Number 240
-Section 12
-Subsection b-2

+ Details

Name:	dei_EntityTaxIdentificationNumber
Namespace Prefix:	dei_
Data Type:	dei:employerIdItemType
Balance Type:	na
Period Type:	duration

- Definition

Local phone number for entity.

+ References

No definition available.

+ Details

Name:	dei_LocalPhoneNumber
Namespace Prefix:	dei_
Data Type:	xbrli:normalizedStringItemType
Balance Type:	na
Period Type:	duration

- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Exchange Act
-Number 240
-Section 13e
-Subsection 4c

+ Details

Name:	dei_PreCommencementIssuerTenderOffer
Namespace Prefix:	dei_
Data Type:	xbrli:booleanItemType
Balance Type:	na
Period Type:	duration

- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Exchange Act
-Number 240
-Section 14d
-Subsection 2b

+ Details

Name:	dei_PreCommencementTenderOffer
Namespace Prefix:	dei_
Data Type:	xbrli:booleanItemType
Balance Type:	na
Period Type:	duration

- Definition

Title of a 12(b) registered security.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Exchange Act
-Number 240
-Section 12
-Subsection b

+ Details

Name:	dei_Security12bTitle
Namespace Prefix:	dei_
Data Type:	dei:securityTitleItemType
Balance Type:	na
Period Type:	duration

- Definition

Name of the Exchange on which a security is registered.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Exchange Act
-Number 240
-Section 12
-Subsection d1-1

+ Details

Name:	dei_SecurityExchangeName
Namespace Prefix:	dei_
Data Type:	dei:edgarExchangeCodeItemType
Balance Type:	na
Period Type:	duration

- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as soliciting material pursuant to Rule 14a-12 under the Exchange Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Exchange Act
-Section 14a
-Number 240
-Subsection 12

+ Details

Name:	dei_SolicitingMaterial
Namespace Prefix:	dei_
Data Type:	xbrli:booleanItemType
Balance Type:	na
Period Type:	duration

- Definition

Trading symbol of an instrument as listed on an exchange.

+ References

No definition available.

+ Details

Name:	dei_TradingSymbol
Namespace Prefix:	dei_
Data Type:	dei:tradingSymbolItemType
Balance Type:	na
Period Type:	duration

- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as written communications pursuant to Rule 425 under the Securities Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Securities Act
-Number 230
-Section 425

+ Details

Name:	dei_WrittenCommunications
Namespace Prefix:	dei_
Data Type:	xbrli:booleanItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	dei_EntityListingsExchangeAxis=exch_XNYS
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=us-gaap_CommonStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=ibm_Notes2.750PercentDue2020Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=ibm_Notes1.875PercentDue2020Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=ibm_Notes0.500PercentDue2021Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=ibm_Notes2.625PercentDue2022Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=ibm_Notes1.25PercentDue2023Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=ibm_Notes0.375PercentDue2023Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=ibm_Notes1.125PercentDue2024Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=ibm_Notes2.875PercentDue2025Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=ibm_Notes0.950PercentDue2025Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=ibm_Notes0.875PercentDue2025Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=ibm_Notes0.300PercentDue2026Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=ibm_Notes1.250PercentDue2027Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=ibm_Notes1.750PercentDue2028Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=ibm_Notes0.300PercentDue2028Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=ibm_Notes1.500PercentDue2029Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=ibm_Notes1.750PercentDue2031Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=ibm_Notes0.650PercentDue2032Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=ibm_Notes1.200PercentDue2040Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=ibm_Debentures7.00PercentDue2025Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=ibm_Debentures6.22PercentDue2027Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=ibm_Debentures6.50PercentDue2028Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=ibm_Debentures7.00PercentDue2045Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=ibm_Debentures7.125PercentDue2096Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_EntityListingsExchangeAxis=exch_XCHI
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: