Note 9 - Income Taxes - Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 26, 2020	Dec. 28, 2019
Inventory, receivable and warranty reserves	$ 11,720	$ 11,235
Net operating loss carryforwards	56,777	69,092
Tax credit carryforwards	37,393	36,489
Accrued employee benefits	5,306	4,274
Stock-based compensation	2,210	2,372
Lease liabilities	5,146	5,804
Other	4,221	9,390
Gross deferred tax assets	122,773	138,656
Less valuation allowance	(86,124)	(93,494)
Total deferred tax assets	36,649	45,162
Intangible assets and other acquisition basis differences	52,012	63,866
Operating lease right-of-use assets	4,706	5,258
Unremitted earnings of foreign subsidiaries	3,119	2,462
Total deferred tax liabilities	59,837	71,586
Net deferred tax liabilities	$ (23,188)	$ (26,424)