| Document and Entity Information | Jul. 02, 2020 |
| Entity Listings [Line Items] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Jul. 2, 2020 |
| Entity Registrant Name | INTERNATIONAL BUSINESS MACHINES CORPORATION |
| Entity Incorporation, State or Country Code | NY |
| Entity File Number | 001-02360 |
| 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 |
| New York Stock Exchange [Member] | Common Stock [Member] | |
| Entity Listings [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 [Member] | 1.875% Notes due 2020 [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | 1.875% Notes due 2020 |
| Trading Symbol | IBM 20A |
| Security Exchange Name | NYSE |
| New York Stock Exchange [Member] | 6.50% Debentures due 2028 [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | 6.50% Debentures due 2028 |
| Trading Symbol | IBM 28 |
| Security Exchange Name | NYSE |
| New York Stock Exchange [Member] | 1.500% Notes due 2029 [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | 1.500% Notes due 2029 |
| Trading Symbol | IBM 29 |
| Security Exchange Name | NYSE |
| New York Stock Exchange [Member] | 1.750% Notes due 2028 [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | 1.750% Notes due 2028 |
| Trading Symbol | IBM 28A |
| Security Exchange Name | NYSE |
| New York Stock Exchange [Member] | 0.500% Notes due 2021 [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | 0.500% Notes due 2021 |
| Trading Symbol | IBM 21B |
| Security Exchange Name | NYSE |
| New York Stock Exchange [Member] | 2.750% Notes due 2020 [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | 2.750% Notes due 2020 |
| Trading Symbol | IBM 20B |
| Security Exchange Name | NYSE |
| New York Stock Exchange [Member] | 2.875% Notes due 2025 [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | 2.875% Notes due 2025 |
| Trading Symbol | IBM 25A |
| Security Exchange Name | NYSE |
| New York Stock Exchange [Member] | 0.650% Notes due 2032 [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | 0.650% Notes due 2032 |
| Trading Symbol | IBM 32 |
| Security Exchange Name | NYSE |
| New York Stock Exchange [Member] | 7.125% Debentures due 2096 [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | 7.125% Debentures due 2096 |
| Trading Symbol | IBM 96 |
| Security Exchange Name | NYSE |
| New York Stock Exchange [Member] | 1.125% Notes due 2024 [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | 1.125% Notes due 2024 |
| Trading Symbol | IBM 24A |
| Security Exchange Name | NYSE |
| New York Stock Exchange [Member] | 1.250% Notes due 2027 [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | 1.250% Notes due 2027 |
| Trading Symbol | IBM 27B |
| Security Exchange Name | NYSE |
| New York Stock Exchange [Member] | 0.875% Notes due 2025 [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | 0.875% Notes due 2025 |
| Trading Symbol | IBM 25C |
| Security Exchange Name | NYSE |
| New York Stock Exchange [Member] | 7.00% Debentures due 2025 [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | 7.00% Debentures due 2025 |
| Trading Symbol | IBM 25 |
| Security Exchange Name | NYSE |
| New York Stock Exchange [Member] | 1.750% Notes due 2031 [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | 1.750% Notes due 2031 |
| Trading Symbol | IBM 31 |
| Security Exchange Name | NYSE |
| New York Stock Exchange [Member] | 0.950% Notes due 2025 [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | 0.950% Notes due 2025 |
| Trading Symbol | IBM 25B |
| Security Exchange Name | NYSE |
| New York Stock Exchange [Member] | 0.300% Notes due 2026 [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | 0.300% Notes due 2026 |
| Trading Symbol | IBM 26B |
| Security Exchange Name | NYSE |
| New York Stock Exchange [Member] | 0.375% Notes due 2023 [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | 0.375% Notes due 2023 |
| Trading Symbol | IBM 23B |
| Security Exchange Name | NYSE |
| New York Stock Exchange [Member] | 7.00% Debentures due 2045 [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | 7.00% Debentures due 2045 |
| Trading Symbol | IBM 45 |
| Security Exchange Name | NYSE |
| New York Stock Exchange [Member] | 6.22% Debentures due 2027 [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | 6.22% Debentures due 2027 |
| Trading Symbol | IBM 27 |
| Security Exchange Name | NYSE |
| New York Stock Exchange [Member] | 1.200% Notes due 2040 [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | 1.200% Notes due 2040 |
| Trading Symbol | IBM 40 |
| Security Exchange Name | NYSE |
| New York Stock Exchange [Member] | 1.250% Notes due 2023 [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | 1.250% Notes due 2023 |
| Trading Symbol | IBM 23A |
| Security Exchange Name | NYSE |
| New York Stock Exchange [Member] | 0.300% Notes due 2028 [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | 0.300% Notes due 2028 |
| Trading Symbol | IBM 28B |
| Security Exchange Name | NYSE |
| New York Stock Exchange [Member] | 2.625% Notes due 2022 [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | 2.625% Notes due 2022 |
| Trading Symbol | IBM 22A |
| Security Exchange Name | NYSE |
| Chicago Stock Exchange, Inc. [Member] | Common Stock [Member] | |
| Entity Listings [Line Items] | |
| Title of 12(b) Security | Capital stock, par value $.20 per share |
| Trading Symbol | IBM |
| Security Exchange Name | CHX |
