Note 7 - Income Taxes - Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 26, 2015
Inventory, receivable and warranty reserves	$ 5,868	$ 8,207
Net operating loss carryforwards	11,681	7,605
Tax credit carryforwards	13,715	12,291
Accrued employee benefits	5,002	4,993
Deferred profit and gain on facility sale	5,412	6,084
Stock-based compensation	4,189	4,443
Acquisition basis differences	1,334	1,544
Other	103	265
Gross deferred tax assets	47,304	45,432
Less valuation allowance	(44,731)	(42,289)
Total deferred tax assets	2,573	3,143
Depreciation and fixed asset related	53	227
Acquisition basis differences	7,423	8,904
Other	662	563
Total deferred tax liabilities	8,138	9,694
Net deferred tax liabilities	$ (5,565)	$ (6,551)