Note 5 - Investments	12 Months Ended
Dec. 31, 2011
Equity Method Investments Disclosure [Text Block]	5. Investments Included in investments are shares of Polytronics Technology Corporation Ltd. (“Polytronics”), a Taiwanese company. The Polytronics investment was acquired as part of the Littelfuse GmbH acquisition. The company’s Polytronics shares held at the end of fiscal 2011 and 2010 represent approximately 7.3% and 8.0% of total Polytronics shares outstanding, respectively. The fair value of the Polytronics investment was €6.8 million (approximately $8.9 million) at December 31, 2011 and €8.8 million (approximately $11.7 million) at January 1, 2011. Included in 2011 other comprehensive income is an unrealized loss of $2.7 million, due to the decrease in fair market value of the Polytronics investment. The remaining movement year over year was due to the impact of changes in exchange rates. 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. The company has accounted for its investment in Shocking Technologies at cost as the fair market value is not readily determinable.

Note 5 - Investments

12 Months Ended

Dec. 31, 2011

Equity Method Investments Disclosure [Text Block]

5. Investments

Included in investments are shares of Polytronics Technology Corporation Ltd. (“Polytronics”), a Taiwanese company. The Polytronics investment was acquired as part of the Littelfuse GmbH acquisition. The company’s Polytronics shares held at the end of fiscal 2011 and 2010 represent approximately 7.3% and 8.0% of total Polytronics shares outstanding, respectively. The fair value of the Polytronics investment was €6.8 million (approximately $8.9 million) at December 31, 2011 and €8.8 million (approximately $11.7 million) at January 1, 2011. Included in 2011 other comprehensive income is an unrealized loss of $2.7 million, due to the decrease in fair market value of the Polytronics investment. The remaining movement year over year was due to the impact of changes in exchange rates.

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. The company has accounted for its investment in Shocking Technologies at cost as the fair market value is not readily determinable.

- Definition

Equity investment disclosure, or group of investments for which combined disclosure is appropriate, including: (a) the name of each investee and percentage of ownership of common stock, (b) accounting policies for investments in common stock, (c) difference between the amount at which the investment is carried and the amount of underlying equity in net assets and the accounting treatment of the difference, (d) the total fair value of each identified investment for which a market value is available, (e) summarized information as to assets, liabilities, and results of operations of the investees (for investments in unconsolidated subsidiaries, common stock of joint ventures, or other investments using the equity method), and (f) material effects of possible conversions, exercises, or contingent issuances of the investee. Other disclosures include (a) the names of any investee in which the investor owns 20 percent or more of the voting stock and investment is not accounted for using the equity method, and the reasons why not, and (b) the names of any investee in which the investor owns less than 20% of the voting stock and the investment is accounted for using the equity method, and the reasons why it is.

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