Document and Entity Information	9 Months Ended
	Sep. 29, 2012
Document and Entity Information [Abstract]
Entity Registrant Name	CADENCE DESIGN SYSTEMS INC
Entity Central Index Key	0000813672
Document Type	10-Q
Document Period End Date	Sep. 29, 2012
Amendment Flag	false
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-29
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding	280,008,255