Document and Entity Information - shares	6 Months Ended
	Jun. 29, 2019	Jul. 30, 2019
Document and Entity Information [Abstract]
Entity Registrant Name	LATTICE SEMICONDUCTOR CORP
Entity Central Index Key	0000855658
Document Type	10-Q
Document Period End Date	Jun. 29, 2019
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--12-28
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		132,668,729