Note 12 - Benefit Plans (Details) (USD $)	3 Months Ended	12 Months Ended								3 Months Ended		12 Months Ended
	Dec. 29, 2012	Dec. 28, 2013	Dec. 28, 2013	Dec. 29, 2012	Dec. 31, 2011	Dec. 31, 2011 Discount Rate [Member] Littelfuse, Inc. Plan [Member]	Dec. 31, 2011 Discount Rate [Member] Cole Hersee Plan [Member]	Dec. 31, 2011 Expected Rate of Return [Member] Littelfuse, Inc. Plan [Member]	Dec. 31, 2011 Expected Rate of Return [Member] Cole Hersee Plan [Member]	Dec. 29, 2012 Selling, General and Administrative Expenses [Member] Amended Plan [Member]	Dec. 29, 2012 Cost of Sales [Member] Manufacturing Facility in Yangmei, Taiwan [Member]	Dec. 31, 2013 United States Pension Plan of US Entity, Defined Benefit [Member]	Dec. 28, 2013 United States Pension Plan of US Entity, Defined Benefit [Member]	Dec. 29, 2012 United States Pension Plan of US Entity, Defined Benefit [Member]	Dec. 31, 2012 United States Pension Plan of US Entity, Defined Benefit [Member]	Dec. 31, 2011 United States Pension Plan of US Entity, Defined Benefit [Member]	Dec. 31, 2013 Foreign Pension Plan, Defined Benefit [Member]	Dec. 28, 2013 Foreign Pension Plan, Defined Benefit [Member]	Dec. 29, 2012 Foreign Pension Plan, Defined Benefit [Member]	Dec. 31, 2012 Foreign Pension Plan, Defined Benefit [Member]	Dec. 31, 2011 Foreign Pension Plan, Defined Benefit [Member]	Dec. 28, 2013 Supplemental Executive Retirement Plan (SERP) [Member]	Dec. 29, 2012 Supplemental Executive Retirement Plan (SERP) [Member]	Dec. 31, 2011 Supplemental Executive Retirement Plan (SERP) [Member]	Dec. 28, 2013 Minimum [Member]	Dec. 28, 2013 Maximum [Member]
Note 12 - Benefit Plans (Details) [Line Items]
Pension Expense	$ 5,300,000			$ 5,100,000						$ 5,100,000	$ 200,000		$ (253,000)	$ 4,378,000		$ (100,000)		$ 1,043,000	$ 1,015,000		$ 589,000
Defined Benefit Plan, Benefit Obligation, Period Increase (Decrease)		5,000,000
			800,000	5,400,000	500,000								(253,000)	(720,000)		(100,000)		1,043,000	827,000		578,000
Defined Benefit Plan, Amount to be Amortized from Accumulated Other Comprehensive Income (Loss) Next Fiscal Year			600,000
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate						5.90%	5.40%	8.50%	7.50%			4.80%			3.90%	5.40%	4.50%			4.20%	5.50%
Defined Benefit Plan, Accumulated Benefit Obligation													84,400,000	95,200,000				46,200,000	12,500,000
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets			6.80%									6.80%			7.80%		4.80%	4.80%		4.50%	4.50%
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay			4.00%																						4.00%	5.00%
Defined Contribution Plan, Employer Discretionary Contribution Amount			1,700,000	1,500,000	1,300,000
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent			90.00%
Defined Contribution Plan, Cost Recognized																						$ 0	$ 100,000	$ 100,000