Note 9 - Income Taxes - Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 25, 2021	Dec. 26, 2020
Inventory, receivable and warranty reserves	$ 12,166	$ 11,720
Net operating loss carryforwards	44,806	56,777
Tax credit carryforwards	31,264	37,393
Accrued employee benefits	5,695	5,306
Stock-based compensation	2,222	2,210
Lease liabilities	4,500	5,146
Other	2,674	4,309
Gross deferred tax assets	103,327	122,861
Less valuation allowance	(76,250)	(86,124)
Total deferred tax assets	27,077	36,737
Intangible assets and other acquisition basis differences	39,929	52,012
Operating lease right-of-use assets	4,066	4,706
Unremitted earnings of foreign subsidiaries	4,207	3,119
Total deferred tax liabilities	48,202	59,837
Net deferred tax liabilities	(21,125)	(23,100)
Other assets (long-term)	4,762	5,716
Long-term deferred income tax liabilities	$ (25,887)	$ (28,816)