Note 12 - Subsequent Event (Details Textual) $ in Millions	Oct. 01, 2015 USD ($)
Subsequent Event [Member] \| Sigmar [Member]
Business Acquisitions, Annual Revenue	$ 6

The annual revenue from the acquired business during the year.

No definition available.

Name:	lfus_BusinessAcquisitionsAnnualRevenue
Namespace Prefix:	lfus_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration