Document and Entity Information	3 Months Ended
	Apr. 04, 2015	May 08, 2015
Document Information [Line Items]
Entity Registrant Name	LATTICE SEMICONDUCTOR CORP
Entity Central Index Key	0000855658
Document Type	10-Q
Document Period End Date	Apr. 04, 2015
Amendment Flag	false
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--01-02
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding (actual number)		116,803,349