Note 3 - Goodwill and Purchased Intangible Assets (Details Textual) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 26, 2015	Dec. 27, 2014
Amortization of Intangible Assets	$ 6.9	$ 7.0	$ 7.8
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	3.6
Finite-Lived Intangible Assets, Amortization Expense, Year Two	3.6
Finite-Lived Intangible Assets, Amortization Expense, Year Three	3.6
Finite-Lived Intangible Assets, Amortization Expense, Year Four	3.5
Finite-Lived Intangible Assets, Amortization Expense, Year Five	0.4
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	$ 3.1