Note 13 - Pensions (Detail) (USD $)	3 Months Ended	12 Months Ended									3 Months Ended		12 Months Ended		3 Months Ended	12 Months Ended
	Dec. 29, 2012	Dec. 29, 2012	Dec. 31, 2011	Jan. 01, 2011	Dec. 31, 2011 Littelfuse, Inc. Plan [Member] Discount Rate [Member]	Dec. 31, 2011 Littelfuse, Inc. Plan [Member] Expected Rate of Return [Member]	Jan. 02, 2010 Littelfuse, Inc. Plan [Member]	Dec. 31, 2011 Cole Hersee Plan [Member] Discount Rate [Member]	Dec. 31, 2011 Cole Hersee Plan [Member] Expected Rate of Return [Member]	Jan. 02, 2010 Cole Hersee Plan [Member]	Dec. 29, 2012 Cost of Sales [Member] Manufacturing Facility in Yangmei, Taiwan [Member]	Dec. 29, 2012 Selling, General and Administrative Expenses [Member] Amended Plan [Member]	Dec. 29, 2012 Minimum [Member]	Dec. 31, 2011 Maximum [Member]	Jan. 01, 2011 German Plan [Member]	Dec. 29, 2012 United States Pension Plans of US Entity, Defined Benefit [Member]	Dec. 31, 2011 United States Pension Plans of US Entity, Defined Benefit [Member]		Jan. 01, 2011 United States Pension Plans of US Entity, Defined Benefit [Member]		Dec. 29, 2012 Foreign Pension Plans, Defined Benefit [Member]	Dec. 31, 2011 Foreign Pension Plans, Defined Benefit [Member]	Jan. 01, 2011 Foreign Pension Plans, Defined Benefit [Member]	Dec. 29, 2012 Supplemental Executive Retirement Plan (SERP) [Member]	Dec. 31, 2011 Supplemental Executive Retirement Plan (SERP) [Member]	Jan. 01, 2011 Supplemental Executive Retirement Plan (SERP) [Member]
Pension Expense	$ 5,300,000	$ 5,100,000									$ 200,000	$ 5,100,000				$ 4,378,000	$ (100,000)		$ (591,000)		$ 1,015,000	$ 589,000	$ 865,000
Pension Contributions															10,200,000
Defined Benefit Plan, Benefit Obligation, Period Increase (Decrease)		5,000,000
		5,400,000	500,000	(300,000)												(720,000)	(100,000)		(591,000)		827,000	578,000	838,000
Pension and Other Postretirement Benefit Plans, Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Fiscal Year		900,000
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate					5.90%	8.50%	5.90%	5.40%	7.50%	5.40%						3.90%	5.40%			[1]	4.20%	5.50%	5.30%
Defined Benefit Plan, Accumulated Benefit Obligation																95,200,000	94,400,000				12,500,000	1,200,000
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets		7.80%														7.80%		[2]	8.50%		4.50%	4.50%	1.50%
Defined Contribution Plan, Employer Matching Contribution, Percent			4.00%										4.00%	5.00%
Defined Contribution Plan, Employer Discretionary Contribution Amount		1,500,000	1,300,000	1,100,000
Defined Contribution Plan, Maximum Annual Contribution Per Employee, Percent			90.00%
Defined Contribution Plan, Cost Recognized																								$ 100,000	$ 100,000	$ 100,000

[1] 5.9% used for the Littelfuse, Inc. Plan, and 5.4% used for the Cole Hersee plan.

[2] 8.5% used for the Littelfuse, inc. Plan, and 7.5% used for the Cole Hersee plan.