Note 14 - Segment Information - Total Assets by Geographic Area (Details) - USD ($) $ in Thousands	Sep. 26, 2020	Dec. 28, 2019	Sep. 28, 2019
Total assets	$ 62,553	$ 96,173	$ 91,740
UNITED STATES
Total assets	39,760	75,724
CANADA
Total assets	14,828	13,770
PUERTO RICO
Total assets	2,105	2,066
SERBIA
Total assets	$ 5,840	$ 4,613