Document and Entity Information (USD $)	12 Months Ended
	Dec. 29, 2012	Mar. 06, 2013	Jun. 29, 2012
Document and Entity Information [Abstract]
Entity Registrant Name	LATTICE SEMICONDUCTOR CORP
Entity Central Index Key	0000855658
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 Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		115,473,147
Entity Current Reporting Status	Yes
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Public Float			$ 289,406,565