Document and Entity Information (USD $)	12 Months Ended
	Jan. 03, 2015	Feb. 26, 2015	Jun. 27, 2014
Document and Entity Information [Abstract]
Entity Registrant Name	LATTICE SEMICONDUCTOR CORP
Entity Central Index Key	0000855658
Document Type	10-K
Document Period End Date	Jan. 03, 2015
Amendment Flag	false
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--01-03
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding (actual number)		116,645,921
Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Filer	No
Entity Public Float			$ 760,876,091