Note 15 - Income Taxes (Details Textual) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 29, 2018	Sep. 30, 2017	Sep. 29, 2018	Sep. 30, 2017	Dec. 30, 2017
Tax Adjustments, Settlements, and Unusual Provisions					$ 1,200
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability					1,000
Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Amount					$ 200
Effective Income Tax Rate Reconciliation, Percent, Total			25.80%	34.70%
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability				$ 781
Effective Income Tax Rate Reconciliation, Excluding Discrete Permanent Differences, Percent				37.90%
Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]
Effective Income Tax Rate Reconciliation, Percent, Total			28.10%	42.50%
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			15.20%