Cover Page	3 Months Ended
	Mar. 31, 2021 shares
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	1-768
Entity Registrant Name	CATERPILLAR INC
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	37-0602744
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
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding	547,763,530
Entity Central Index Key	0000018230
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Common Stock
Entity Information [Line Items]
Title of 12(b) Security	Common Stock ($1.00 par value)
Trading Symbol	CAT
Security Exchange Name	NYSE
8% Debentures due February 15, 2023
Entity 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
Entity Information [Line Items]
Title of 12(b) Security	5.3% Debentures due September 15, 2035
Trading Symbol	CAT35
Security Exchange Name	NYSE