Document and Entity Information - shares	6 Months Ended
	Jul. 01, 2017	Aug. 07, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	LATTICE SEMICONDUCTOR CORP
Entity Central Index Key	0000855658
Document Type	10-Q
Document Period End Date	Jul. 01, 2017
Amendment Flag	false
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--12-30
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding (actual number)		122,971,647