Document And Entity Information - shares	9 Months Ended
	Oct. 02, 2021	Oct. 28, 2021
Document Information [Line Items]
Entity Central Index Key	0000855658
Entity Registrant Name	Lattice Semiconductor Corp
Amendment Flag	false
Current Fiscal Year End Date	--01-01
Document Fiscal Period Focus	Q3
Document Fiscal Year Focus	2021
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Oct. 02, 2021
Document Transition Report	false
Entity File Number	000-18032
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	93-0835214
Entity Address, Address Line One	5555 NE Moore Court
Entity Address, City or Town	Hillsboro
Entity Address, State or Province	OR
Entity Address, Postal Zip Code	97124
City Area Code	503
Local Phone Number	268-8000
Title of 12(b) Security	Common Stock, $.01 par value
Trading Symbol	LSCC
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		136,939,698