Note 3 - Goodwill and Purchased Intangible Assets (Details Textual) - USD ($) $ in Millions	12 Months Ended
	Dec. 30, 2017	Dec. 31, 2016	Dec. 26, 2015
Amortization of Intangible Assets	$ 4.2	$ 6.9	$ 7.0
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	4.2
Finite-Lived Intangible Assets, Amortization Expense, Year Two	4.2
Finite-Lived Intangible Assets, Amortization Expense, Year Three	4.1
Finite-Lived Intangible Assets, Amortization Expense, Year Four	0.7
Finite-Lived Intangible Assets, Amortization Expense, Year Five	0.7
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	$ 2.8