Note 9 - Income Taxes (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 25, 2021	Dec. 26, 2020
Deferred Tax Assets, Valuation Allowance	$ 89,234	$ 76,250
Increase (Decrease) of Net Income Due to Impact of Tax Holidays		$ 4,500	$ 3,600
Increase (Decrease) of Earning Per Share Due To Impact Of Tax Holidays (in dollars per share)		$ 0.09	$ 0.09
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	5,800	$ 5,300	$ 5,900
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued, Total	600	800
Unrecognized Tax Benefits, Interest Expense, Net of Accrued Interest Reversed	$ (100)	$ (200)	$ (300)
Minimum [Member]
Collection Term Range (Year)	4 years
Maximum [Member]
Collection Term Range (Year)	10 years
Domestic Tax Authority [Member]
Operating Loss Carryforwards	$ 140,000
Tax Credit Carryforward, Amount	3,700
State and Local Jurisdiction [Member]
Operating Loss Carryforwards	113,900
Tax Credit Carryforward, Amount	32,900
Foreign Tax Authority [Member]
Operating Loss Carryforwards	$ 9,000