Note 15 - Income Taxes (Details Textual) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 29, 2019	Mar. 30, 2019	Jun. 30, 2018	Jun. 29, 2019	Jun. 30, 2018
Income Tax Expense (Benefit), Total	$ 459		$ 121	$ 185	$ 483
Effective Income Tax Rate Reconciliation, Tax Settlement, Domestic, Amount		$ 600
Effective Income Tax Rate Reconciliation, Percent, Total				27.10%	25.20%
Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]
Effective Income Tax Rate Reconciliation, Percent, Total				28.60%	28.30%
Foreign Tax Authority [Member] | Canada Revenue Agency [Member]
Effective Income Tax Rate Reconciliation, Percent, Total				26.50%	26.50%
Foreign Tax Authority [Member] | Ministry of Finance, Republic of Serbia [Member]
Effective Income Tax Rate Reconciliation, Percent, Total				15.00%	17.30%