Note 15 - Income Taxes (Details Textual) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2020	Sep. 28, 2019	Sep. 26, 2020	Sep. 28, 2019
Income Tax Expense (Benefit), Total	$ (167)	$ 70	$ (2,815)	$ 255
Effective Income Tax Rate Reconciliation, Percent, Total			28.20%	25.90%
Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]
Effective Income Tax Rate Reconciliation, Percent, Total			27.00%	28.30%
Foreign Tax Authority [Member] | Canada Revenue Agency [Member]
Effective Income Tax Rate Reconciliation, Percent, Total			26.70%	26.50%
Foreign Tax Authority [Member] | Ministry of Finance, Republic of Serbia [Member]
Effective Income Tax Rate Reconciliation, Percent, Total			15.10%	15.00%