Income Tax Holiday Expense (Benefit) Amount Per Diluted Share.

No definition available.

Name:	lfus_IncomeTaxHolidayExpenseBenefitAmountPerDilutedShare
Namespace Prefix:	lfus_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	lfus_Note14IncomeTaxesDetailsLineItems
Namespace Prefix:	lfus_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4297-108586

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 25

-Subparagraph (f)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3536-108585

+ Details

Name:	us-gaap_IncomeTaxesPaid
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount of income taxes from which a reporting entity is exempt or for which it will receive a reduction in income taxes as a result of the income tax holiday granted by the taxing jurisdiction.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SAB TOPIC 11.C)

-URI http://asc.fasb.org/extlink&oid=34349781&loc=d3e330215-122817

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 11

-Section C

+ Details

Name:	us-gaap_IncomeTaxHolidayAggregateDollarAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of undistributed earnings of foreign subsidiaries intended to be permanently reinvested outside the country of domicile.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (b)(c)

-URI http://asc.fasb.org/extlink&oid=6424122&loc=d3e41874-109331

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 740

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6479915&loc=d3e66715-112838

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 740

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6487024&loc=d3e29054-158556

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 995

-SubTopic 740

-Section 50

-Paragraph 2

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6503627&loc=d3e59836-110443

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 25

-Paragraph 3

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=29652012&loc=d3e28200-109314

+ Details

Name:	us-gaap_UndistributedEarningsOfForeignSubsidiaries
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Unrecognized Tax Benefit

-URI http://asc.fasb.org/extlink&oid=6527854

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 15A

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6907707&loc=SL6600010-109319

+ Details

Name:	us-gaap_UnrecognizedTaxBenefits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 15A

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6907707&loc=SL6600010-109319

+ Details

Name:	us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_StatementGeographicalAxis=country_CN
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Note 14 - Income Taxes (Details) (USD $)	12 Months Ended
Note 14 - Income Taxes (Details) (USD $)	Dec. 27, 2014	Dec. 28, 2013	Dec. 29, 2012	Dec. 31, 2011
Note 14 - Income Taxes (Details) [Line Items]
Income Taxes Paid	$ 26,600,000us-gaap_IncomeTaxesPaid	$ 30,400,000us-gaap_IncomeTaxesPaid	$ 23,800,000us-gaap_IncomeTaxesPaid
Undistributed Earnings of Foreign Subsidiaries	351,200,000
Unrecognized Tax Benefits	112,000us-gaap_UnrecognizedTaxBenefits			112,000us-gaap_UnrecognizedTaxBenefits
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	100,000
CHINA
Note 14 - Income Taxes (Details) [Line Items]
Income Tax Holiday, Aggregate Dollar Amount	$ 3,000,000
Income Tax Holiday Expense (Benefit) Amount Per Diluted Share (in Dollars per share) (in Dollars per share)	$ 0.13