Document and Entity Information - shares	6 Months Ended
	Jul. 04, 2015	Aug. 07, 2015
Document Information [Line Items]
Entity Registrant Name	LATTICE SEMICONDUCTOR CORP
Entity Central Index Key	0000855658
Document Type	10-Q
Document Period End Date	Jul. 04, 2015
Amendment Flag	false
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--01-02
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding (actual number)		117,616,304