Document and Entity Information - USD ($)	12 Months Ended
	Dec. 29, 2018	Feb. 21, 2019	Jun. 29, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	LATTICE SEMICONDUCTOR CORP
Entity Central Index Key	0000855658
Document Type	10-K
Document Period End Date	Dec. 29, 2018
Amendment Flag	false
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-29
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		131,598,332
Entity Shell Company	false
Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Filer	No
Entity Public Float			$ 575,075,952