Note 13 - Employee Benefit Plans (Details Textual) - USD ($) $ in Millions	12 Months Ended
Jan. 02, 2021	Dec. 28, 2019	Dec. 29, 2018
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 2.4	$ 0.8	$ 0.6
Labor And Related Expense, Incentive Compensation	$ 7.9	$ 5.8	$ 5.9

Amount of expense for salary, wage, profit sharing; incentive and equity-based compensation; and other employee benefit.

No definition available.

Name:	lscc_LaborAndRelatedExpenseIncentiveCompensation
Namespace Prefix:	lscc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration