Note 7 - Income Taxes - Reconciliation of Income Tax Computed at U.S. Federal Statutory Tax Rate to Provision (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 26, 2015	Dec. 27, 2014
Tax provision at U.S. 35% statutory rate	$ 2,102	$ 2,801	$ 6,802
State income taxes, net of federal tax benefit	168	(152)	119
Settlements, adjustments and releases from statute expirations	(312)	(104)	(65)
Federal tax credits	(183)	(221)	(244)
Stock-based compensation on which no tax benefit provided	168	156	160
Change in valuation allowance	2,430	2,181	437
Non-deductible transaction costs	463
Foreign income taxed at different rates	(2,378)	(2,601)	(2,151)
Other, net	289	151	(405)
	$ 2,747	$ 2,211	$ 4,653