Document and Entity Information	3 Months Ended
	Mar. 28, 2014	Apr. 10, 2014
Document and Entity Information [Abstract]
Entity Registrant Name	ALTERA CORP
Entity Central Index Key	0000768251
Document Type	10-Q
Document Period End Date	Mar. 28, 2014
Amendment Flag	false
Document Fiscal Year	2014
Document Fiscal Period	Q1
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		313,256,406