Percentage of vesting of award under share-based payment arrangement based on market conditions.

No definition available.

Name:	lscc_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentageBasedOnMarketConditions
Namespace Prefix:	lscc_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The percentage of market condition achieved for awards to vest under share based payment arrangement that was exceeded.

+ References

No definition available.

+ Details

Name:	lscc_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentageBasedOnMarketConditionsExceeded
Namespace Prefix:	lscc_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of vesting of award under share-based payment arrangement based on stock price appreciation.

+ References

No definition available.

+ Details

Name:	lscc_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentageBasedOnSockPriceAppreciation
Namespace Prefix:	lscc_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The percentage of market condition achieved for awards to vest under share based payment arrangement.

+ References

No definition available.

+ Details

Name:	lscc_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentageOfMarketConditionAchieved
Namespace Prefix:	lscc_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The maximum annual contribution percentage per employee that can be used under the plan.

+ References

No definition available.

+ Details

Name:	lscc_SharebasedCompensationArrangementBySharebasedPaymentAwardMaximumAnnualContributionPerEmployeePercent
Namespace Prefix:	lscc_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of vesting of award under share-based payment arrangement.

+ References

No definition available.

+ Details

Name:	lscc_SharebasedCompensationArrangementBySharebasedPaymentAwardPercentageAwardVestingRights
Namespace Prefix:	lscc_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of benefit from forfeitures under share-based payment arrangement.

+ References

No definition available.

+ Details

Name:	lscc_SharebasedPaymentArrangementBenefitFromForfeitures
Namespace Prefix:	lscc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the tax benefit related to the share-based payment arrangement of exercised and vesting awards.

+ References

No definition available.

+ Details

Name:	lscc_SharebasedPaymentArrangementExerciseAndVestingOfAwardsTaxBenefit
Namespace Prefix:	lscc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section S45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479983/718-10-S45-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.F)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479830/718-10-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

+ Details

Name:	us-gaap_AllocatedShareBasedCompensationExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of cost to be recognized for nonvested award under share-based payment arrangement. Excludes share and unit options.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of tax benefit for recognition of expense of award under share-based payment arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Estimated period over which an employee is required to provide service in exchange for the equity-based payment award, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(01)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Purchase price of common stock expressed as a percentage of its fair value.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-4

+ Details

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_AwardTypeAxis=lscc_AwardsVestedOrExercisedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=lscc_EmployeeStockPurchasePlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_RestrictedStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_TitleOfIndividualAxis=srt_ExecutiveOfficerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_RestrictedStockUnitsRSUMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VestingAxis=us-gaap_ShareBasedCompensationAwardTrancheOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VestingAxis=us-gaap_ShareBasedCompensationAwardTrancheTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_TitleOfIndividualAxis=srt_ChiefExecutiveOfficerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VestingAxis=us-gaap_ShareBasedCompensationAwardTrancheThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_PerformanceSharesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=lscc_AwardsGrantedIn2022And2021Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=lscc_AwardsWithMarketConditionOrPerformanceConditionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VestingAxis=lscc_TsrRelativeToPhlxSemiconductorSectorIndex75thPercentileMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=lscc_The2012ESPPMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=lscc_The2023EquityIncentivePlanAndThe2011NonemployeeDirectorEquityIncentivePlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=lscc_The2025InducementEquityPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Note 10 - Stock-based Compensation Plans (Details Textual) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions	9 Months Ended	12 Months Ended
	Sep. 28, 2024	Jan. 03, 2026	Dec. 28, 2024	Dec. 30, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period (Year)		4 years
Share-Based Payment Arrangement, Expense, Tax Benefit		$ 8,500	$ 6,300	$ 7,600
Share-Based Payment Arrangement, Expense		115,613	$ 52,985	70,197
Awards Vested or Exercised [Member]
Share-Based Payment Arrangement, Exercise and Vesting of Awards, Tax Benefit		$ 1,700		$ 10,400
Employee Stock Purchase Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share)		$ 18.3	$ 15.5	$ 24.38
Share-Based Payment Arrangement, Expense		$ 2,300	$ 1,800	$ 2,200
Restricted Stock [Member]
Share-Based Payment Arrangement, Expense		70,200	$ 51,800	$ 41,500
Share-Based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount		$ 162,900
Restricted Stock [Member] \| Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Of Market Condition Achieved			75.00%
Restricted Stock Units (RSUs) [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share)		$ 51.54
Restricted Stock Units (RSUs) [Member] \| Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Of Market Condition Achieved		75.00%		75.00%
Restricted Stock Units (RSUs) [Member] \| Executive Officer [Member] \| Share-Based Payment Arrangement, Tranche One [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period (Year)			3 years	13 months
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage, Based on Market Conditions		100.00%
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Of Market Condition Achieved		55.00%		200.00%
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage, Based on Market Conditions, Exceeded		134.00%
Restricted Stock Units (RSUs) [Member] \| Executive Officer [Member] \| Share-Based Payment Arrangement, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage, Based on Market Conditions		0.00%
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Of Market Condition Achieved		25.00%
Restricted Stock Units (RSUs) [Member] \| Chief Executive Officer [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Requisite Service Period (Year)			6 years
Restricted Stock Units (RSUs) [Member] \| Chief Executive Officer [Member] \| Share-Based Payment Arrangement, Tranche Three [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period (Year)		3 years
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage, Based on Market Conditions		116.30%
Performance Shares [Member] \| Executive Officer [Member] \| Share-Based Payment Arrangement, Tranche One [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period (Year)			13 months
Awards Granted in 2022 and 2021 [Member] \| Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage, Based on Market Conditions			97.00%
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Of Market Condition Achieved			54.00%
Awards Granted in 2022 and 2021 [Member] \| Executive Officer [Member] \| Share-Based Payment Arrangement, Tranche Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Of Market Condition Achieved	116.30%
Awards with Market Condition or Performance Condition [Member]
Share-Based Payment Arrangement, Expense		$ 43,100	$ 28,400	$ 26,400
Share-Based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount		$ 66,200
Share-Based Payment Arrangement, Benefit From Forfeitures			$ 29,000
Minimum [Member] \| Restricted Stock [Member] \| Executive Officer [Member] \| Share-Based Payment Arrangement, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage, Based on Market Conditions			200.00%
Minimum [Member] \| Restricted Stock Units (RSUs) [Member] \| Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Of Market Condition Achieved				200.00%
Minimum [Member] \| Restricted Stock Units (RSUs) [Member] \| Executive Officer [Member] \| TSR Relative To PHLX Semiconductor Sector Index, 75th Percentile [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage, Based on Market Conditions		200.00%
Minimum [Member] \| Restricted Stock Units (RSUs) [Member] \| Executive Officer [Member] \| Share-Based Payment Arrangement, Tranche Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Of Market Condition Achieved		25.00%
Minimum [Member] \| Restricted Stock Units (RSUs) [Member] \| Chief Executive Officer [Member] \| Share-Based Payment Arrangement, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Percentage, Award Vesting Rights			25.00%
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage, Based on Sock Price Appreciation			25.00%
Minimum [Member] \| Awards Granted in 2022 and 2021 [Member] \| Executive Officer [Member] \| Share-Based Payment Arrangement, Tranche Two [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period (Year)			13 months
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage, Based on Market Conditions			200.00%
Maximum [Member] \| Restricted Stock [Member] \| Executive Officer [Member] \| Share-Based Payment Arrangement, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage, Based on Market Conditions			250.00%
Maximum [Member] \| Restricted Stock Units (RSUs) [Member] \| Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Of Market Condition Achieved				250.00%
Maximum [Member] \| Restricted Stock Units (RSUs) [Member] \| Executive Officer [Member] \| TSR Relative To PHLX Semiconductor Sector Index, 75th Percentile [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage, Based on Market Conditions		250.00%
Maximum [Member] \| Restricted Stock Units (RSUs) [Member] \| Executive Officer [Member] \| Share-Based Payment Arrangement, Tranche Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Of Market Condition Achieved		75.00%
Maximum [Member] \| Restricted Stock Units (RSUs) [Member] \| Chief Executive Officer [Member] \| Share-Based Payment Arrangement, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Percentage, Award Vesting Rights			250.00%
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage, Based on Sock Price Appreciation			200.00%
Maximum [Member] \| Performance Shares [Member] \| Executive Officer [Member] \| Share-Based Payment Arrangement, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Percentage, Award Vesting Rights			250.00%
The2012 ESPP [Member]
Share-based Compensation Arrangement By Share-based Payment Award, Maximum, Annual Contribution Per Employee, Percent		10.00%
Share-Based Compensation Arrangement by Share-Based Payment Award, Purchase Price of Common Stock, Percent		85.00%
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant (in shares)		0.7
The2012 ESPP [Member] \| Minimum [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Purchase Price of Common Stock, Percent		85.00%
The 2023 Equity Incentive Plan and the 2011 Non-Employee Director Equity Incentive Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant (in shares)		4.9
The 2025 Inducement Equity Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant (in shares)		1.3