Note 14 - Segment Information - Revenues by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2020	Sep. 28, 2019	Sep. 26, 2020	Sep. 28, 2019
Revenues	$ 31,561	$ 40,250	$ 109,246	$ 142,550
UNITED STATES
Revenues	25,628	34,810	91,793	124,356
CANADA
Revenues	3,543	3,682	11,186	12,770
PUERTO RICO
Revenues	1,433	1,215	4,018	3,627
SERBIA
Revenues	$ 957	$ 543	$ 2,249	$ 1,797