Document and Entity Information	9 Months Ended
	Sep. 30, 2018 shares
Document and Entity Information
Entity Registrant Name	INTERNATIONAL BUSINESS MACHINES CORP
Entity Central Index Key	0000051143
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding	908,793,777
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q3
Trading Symbol	IBM