Note 1 - Summary of Significant Accounting Policies - Customer Concentration (Details) - Sales Revenue, Net [Member] - Customer Concentration Risk [Member]	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 24, 2016	Sep. 30, 2017	Sep. 24, 2016
Customers individually accounting for more than 10% of net sales	2	3	2	2
Two Customers [Member]
Percentage of net sales	26.50%		28.50%	30.50%
Three Customers [Member]
Percentage of net sales		37.40%