Document And Entity Information	3 Months Ended
	Mar. 30, 2013	Apr. 26, 2013
Document and Entity Information [Abstract]
Entity Registrant Name	LITTELFUSE INC /DE
Document Type	10-Q
Current Fiscal Year End Date	--12-29
Entity Common Stock, Shares Outstanding		22,106,477
Amendment Flag	true
Amendment Description	Littelfuse, Inc. (?we? or the ?company?) is filing this report on Form 10-Q/A because the Audit Committee of the Board of Directors (the ?Committee?) approved, on February 4, 2014, management?s recommendation that the company?s previously issued financial statements included in the company?s quarterly report on form 10-Q for the fiscal quarter ended March 30, 2013, and filed on May 3, 2013 (?Original Form 10-Q?), should no longer be relied upon because of an error resulting from the treatment of tax deductions related to the company?s write-off of its investment in Shocking Technologies, Inc. The tax deductions were determined to be a capital loss for tax purposes, instead of an ordinary loss as the company had previously determined in consultation with a third party expert. The impact of correcting this error is to record a charge to income tax expense of $3.3 million relating to the company?s first fiscal quarter ended March 30, 2013. As a result, the income tax expense recorded by the company in the first quarter of fiscal 2013 was understated by $3.3 million, producing an overstatement of net income of $3.3 million. The error was discovered in connection with the annual audit of the company for its fiscal year ended December 28, 2013. On February 4, 2014, the Committee approved management?s recommendation that the company restate its financial statements for the three months ended March 30, 2013, by filing on this Form 10-Q/A an amendment to the Original Form 10-Q. Prior to the February 4, 2014, determination, management and the Audit Committee discussed these matters with Ernst and Young LLP, the company?s independent registered public accounting firm. The company filed an Item 4.02 current report on Form 8-K on February 5, 2014, relating to this matter. The company believes the restatement constitutes a material weakness and that its disclosure controls and procedures were not effective as of the end of the period covered by the Original Form 10-Q. Management has commenced steps to remediate the material weakness associated with the income tax valuation allowance misstatement. For more information on the material weakness and our remediation efforts, please see ?Item 4 ? Controls and Procedures? of this Form 10-Q/A. This report on Form 10-Q/A restates in its entirety the Original Form 10-Q. The following sections of the Original Form 10-Q have been restated: (1) Item 1 of Part I, Financial Statements, (2) Item 2 of Part I, Management?s Discussion and Analysis of Financial Condition and Results of Operations, and (3) Item 4 of Part I, Controls and Procedures. Specifically the following sections have been restated or added: (1) Condensed Consolidated Balance Sheets, (2) Consolidated Statements of Net Income, (3) Consolidated Statements of Comprehensive Income (4) Consolidated Statements of Cash Flows, (5) Note 1. Basis of Presentation (6) Note 9. Earnings Per Share (7) Note 11. Income Taxes (8) Note 15. Subsequent Event, and (9) Note 16. Restatement. The company has also restated the signature page, the certifications of our Chief Executive Officer and Chief Financial Officer in Exhibits 31.1, 31.2, and 32.1, and the financial statements formatted in Extensible Business Reporting Language (XBRL) in Exhibits 101. No other sections were affected. For more information about the restatement and the related disclosure controls and procedures matters, please see Littelfuse?s Current Report on Form 8-K (Item 4.02) filed on February 5, 2014.
Entity Central Index Key	0000889331
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Well-known Seasoned Issuer	Yes
Document Period End Date	Mar. 30, 2013
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q1