Document And Entity Information (USD $) In Billions, except Share data in Millions, unless otherwise specified	12 Months Ended
	Oct. 31, 2011	Dec. 03, 2011	Apr. 30, 2011
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Oct. 31, 2011
Entity Registrant Name	SYNOPSYS INC
Entity Central Index Key	0000883241
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--10-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		144.2
Trading Symbol	snps
Entity Voluntary Filers	No
Entity Public Float			$ 2.5
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes