v3.26.1

Cover Page - shares	3 Months Ended
Cover Page - shares	Mar. 28, 2026	May 01, 2026
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 28, 2026
Document Transition Report	false
Entity File Number	0-20388
Entity Registrant Name	LITTELFUSE INC /DE
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	36-3795742
Entity Address, Address Line One	6133 North River Road
Entity Address, Address Line Two	Suite 500
Entity Address, City or Town	Rosemont
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	60018
City Area Code	773
Local Phone Number	628-1000
Title of 12(b) Security	Common Stock, $0.01 par value
Trading Symbol	LFUS
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		25,288,904
Entity Central Index Key	0000889331
Current Fiscal Year End Date	--12-26
Document Fiscal Year Focus	2026
Document Fiscal Period Focus	Q1
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LITTELFUSE INC /DE 10-Q