Document and Entity Information	6 Months Ended
	Jun. 30, 2018 shares
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	Jun. 30, 2018
Amendment Flag	false
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--12-29
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding	282,808,000