Cover
| Cover | Mar. 12, 2021 |
| Document Information [Line Items] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Mar. 12, 2021 |
| Entity File Number | 1-768 |
| Entity Registrant Name | CATERPILLAR INC. |
| Entity Central Index Key | 0000018230 |
| Entity Tax Identification Number | 37-0602744 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 510 Lake Cook Road |
| Entity Address, Address Line Two | Suite 100 |
| Entity Address, City or Town | Deerfield |
| Entity Address, State or Province | IL |
| Entity Address, Postal Zip Code | 60015 |
| City Area Code | (224) |
| Local Phone Number | 551-4000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Common Stock | |
| Document Information [Line Items] | |
| Title of 12(b) Security | Common Stock ($1.00 par value) |
| Trading Symbol | CAT |
| Security Exchange Name | NYSE |
| 9 3/8% Debentures Due March15, 2021 | |
| Document Information [Line Items] | |
| Title of 12(b) Security | 9 3/8% Debentures due March 15, 2021 |
| Trading Symbol | CAT21 |
| Security Exchange Name | NYSE |
| 8% Debentures Due February 15, 2023 | |
| Document Information [Line Items] | |
| Title of 12(b) Security | 8% Debentures due February 15, 2023 |
| Trading Symbol | CAT23 |
| Security Exchange Name | NYSE |
| 5.3% Debentures Due September 15, 2035 | |
| Document Information [Line Items] | |
| Title of 12(b) Security | 5.3% Debentures due September 15, 2035 |
| Trading Symbol | CAT35 |
| Security Exchange Name | NYSE |