Note 11 - Income Taxes (Details Textual) $ in Millions	9 Months Ended	27 Months Ended
Oct. 04, 2015 USD ($)	Oct. 04, 2015 USD ($)
Unrecognized Tax Benefits, Period Increase (Decrease)	$ (0.1)
Unrecognized Tax Benefits	$ 27.3	$ 27.3
Increase (Decrease) in Deferred Tax Assets		$ (21.9)

The increase (decrease) during the reporting period in the account that represents the deferred tax asset attributable to deductible temporary differences and carryforwards.

No definition available.

+ Details

Name:	tile_IncreaseDecreaseInDeferredTaxAssets
Namespace Prefix:	tile_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- 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

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 15A

-Subparagraph (a)

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

Reference 2: 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

+ Details

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

- Definition

The net amount of all increases and decreases in unrecognized tax benefits for the period.

+ References

+ Details

Name:	us-gaap_UnrecognizedTaxBenefitsPeriodIncreaseDecrease
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration