Note 15 - Commitments and Contigencies (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 28, 2014	Dec. 29, 2013	Dec. 30, 2012	Jan. 01, 2012
Commitments and Contingencies Disclosure [Abstract]
Operating Leases, Rent Expense	$ 24.6us-gaap_LeaseAndRentalExpense	$ 24.5us-gaap_LeaseAndRentalExpense	$ 22.8us-gaap_LeaseAndRentalExpense
Rental Expenses Related to Discontinued Operations				$ 2.6

Amount of rent expense incurred for leased assets, including but not limited to, furniture and equipment, that is not directly or indirectly associated with the manufacture, sale or creation of a product or product line related to discontinued operations.

No definition available.

Name:	tile_RentalExpensesRelatedToDiscontinuedOperations
Namespace Prefix:	tile_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration