Document and Entity Information (USD $)	12 Months Ended
	Dec. 29, 2012	Feb. 02, 2013	Jun. 30, 2012
Document and Entity Information [Abstract]
Entity Registrant Name	CADENCE DESIGN SYSTEMS INC
Entity Central Index Key	0000813672
Document Type	10-K
Document Period End Date	Dec. 29, 2012
Amendment Flag	false
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-29
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 3,021,086,192
Entity Common Stock, Shares Outstanding		281,707,719