Note 4 - Investments	6 Months Ended
Jun. 30, 2012
Equity Method Investments and Joint Ventures Disclosure [Text Block]	4. Investments Included in the company’s investments are shares of Polytronics Technology Corporation Ltd. (“Polytronics”), a Taiwanese company whose shares are traded on the Taiwan Stock Exchange. The Polytronics investment was acquired as part of the Littelfuse GmbH acquisition. The fair value of the Polytronics investment was €9.2 million (approximately $11.5 million) at June 30, 2012 and €6.8 million (approximately $8.9 million) at December 31, 2011, based on the quoted market price at the close of business corresponding to each date. Included in Other Comprehensive Income (Loss), for the six months ended June 30, 2012, is an unrealized gain of $3.1 million, due to the increase in fair market value. The remaining difference in fair market value of this investment was due to the impact of changes in exchange rates, which is included as a component of the currency translation adjustments of Other Comprehensive Income (Loss). In 2011, the company invested $6.0 million in certain preferred stock of Shocking Technologies, Inc. (“Shocking Technologies”), a research and development company in the electronics industry located in San Jose, California. Shocking Technologies is a developer of circuit protection products for the computer and telecommunication markets. In April 2012, the company made an additional $10.0 million investment. The company has now invested $16.0 million in Shocking Technologies for an ownership stake of approximately 18%. The company has accounted for its investment in Shocking Technologies, Inc. at cost as the company does not exert significant influence thereon and as the fair value of the investment is not readily determinable.

Note 4 - Investments

6 Months Ended

Jun. 30, 2012

Equity Method Investments and Joint Ventures Disclosure [Text Block]

4. Investments

Included in the company’s investments are shares of Polytronics Technology Corporation Ltd. (“Polytronics”), a Taiwanese company whose shares are traded on the Taiwan Stock Exchange. The Polytronics investment was acquired as part of the Littelfuse GmbH acquisition. The fair value of the Polytronics investment was €9.2 million (approximately $11.5 million) at June 30, 2012 and €6.8 million (approximately $8.9 million) at December 31, 2011, based on the quoted market price at the close of business corresponding to each date. Included in Other Comprehensive Income (Loss), for the six months ended June 30, 2012, is an unrealized gain of $3.1 million, due to the increase in fair market value. The remaining difference in fair market value of this investment was due to the impact of changes in exchange rates, which is included as a component of the currency translation adjustments of Other Comprehensive Income (Loss).

In 2011, the company invested $6.0 million in certain preferred stock of Shocking Technologies, Inc. (“Shocking Technologies”), a research and development company in the electronics industry located in San Jose, California. Shocking Technologies is a developer of circuit protection products for the computer and telecommunication markets. In April 2012, the company made an additional $10.0 million investment. The company has now invested $16.0 million in Shocking Technologies for an ownership stake of approximately 18%. The company has accounted for its investment in Shocking Technologies, Inc. at cost as the company does not exert significant influence thereon and as the fair value of the investment is not readily determinable.

- Definition

The entire disclosure for equity method investments and joint ventures. Equity method investments are investments that give the investor the ability to exercise significant influence over the operating and financial policies of an investee. Joint ventures are entities owned and operated by a small group of businesses as a separate and specific business or project for the mutual benefit of the members of the group.

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