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v3.25.1

Summary of Significant Accounting Policies and Other Information - Narrative (Details) customer in Thousands, associate in Thousands | 3 Months Ended
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Mar. 29, 2025 associate country customer
Accounting Policies [Abstract] |
Countries where product is used (more than) (country) | country | 20
Global associates (associate) | associate | 16
Number of customers (over) | customer | 100

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- Definition Global Associates + References No definition available. + Details
Name: | lfus_GlobalAssociates
Namespace Prefix: | lfus_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

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- Definition The number of customers that a company has. + References No definition available. + Details
Name: | lfus_NumberOfCustomers
Namespace Prefix: | lfus_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

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- References No definition available. + Details
Name: | us-gaap_AccountingPoliciesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition The number of countries in which the entity operates as of balance sheet date. + References No definition available. + Details
Name: | us-gaap_NumberOfCountriesInWhichEntityOperates
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant