Note 11 - Coal Mine Liability	12 Months Ended
Dec. 29, 2012
Other Liabilities Disclosure [Text Block]	11. Coal Mine Liability Included in other long-term liabilities is an accrual related to former coal mining operations at Littelfuse GmbH (formerly known as Heinrich Industries, AG) for the amounts of €2.4 million ($3.1 million) and €3.1 million ($4.0 million) at December 29, 2012 and December 31, 2011, respectively. Management accrues for losses associated with litigation and environmental claims based on management's best estimate of future costs when such losses are probable and reasonably able to be estimated. Management, in conjunction with an independent third-party used to prepare an annual engineering study, performs an annual evaluation of the former coal mining operations in order to develop its estimate of their probable future obligations in regard to remediating the dangers (such as a shaft collapse) of abandoned coal mine shafts in the former coal mining operations. The ultimate determination can only be done after respective investigations because the concrete conditions are mostly unknown at this time. The accrual is not discounted as management cannot reasonably estimate when such remediation efforts will take place.

Note 11 - Coal Mine Liability

12 Months Ended

Dec. 29, 2012

Other Liabilities Disclosure [Text Block]

11. Coal Mine Liability

Included in other long-term liabilities is an accrual related to former coal mining operations at Littelfuse GmbH (formerly known as Heinrich Industries, AG) for the amounts of €2.4 million ($3.1 million) and €3.1 million ($4.0 million) at December 29, 2012 and December 31, 2011, respectively. Management accrues for losses associated with litigation and environmental claims based on management's best estimate of future costs when such losses are probable and reasonably able to be estimated. Management, in conjunction with an independent third-party used to prepare an annual engineering study, performs an annual evaluation of the former coal mining operations in order to develop its estimate of their probable future obligations in regard to remediating the dangers (such as a shaft collapse) of abandoned coal mine shafts in the former coal mining operations. The ultimate determination can only be done after respective investigations because the concrete conditions are mostly unknown at this time. The accrual is not discounted as management cannot reasonably estimate when such remediation efforts will take place.