Note 8 - Income Taxes (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 28, 2019	Dec. 29, 2018	Dec. 30, 2017
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%	35.00%
Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Amount	$ 5,100		$ 16,600
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability			(4,000)
Deferred Tax Assets, Valuation Allowance, Total	93,498	$ 84,718
Increase (Decrease) of Net Income Due to Impact of Tax Holidays	$ 2,100	$ 2,400	$ 2,800
Increase (Decrease) of Earning Per Share Due To Impact Of Tax Holidays	$ 0.05	$ 0.08	$ 0.10
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	$ 7,000	$ 8,200
Decrease in Unrecognized Tax Benefits is Reasonably Possible	400
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued, Total	1,300	1,500
Unrecognized Tax Benefits, Interest Expense, Net of Accrued Interest Reversed	(300)	$ 600	$ (300)
Minimum [Member]
Collection Term Range		4 years
Maximum [Member]
Collection Term Range		10 years
Domestic Tax Authority [Member]
Operating Loss Carryforwards, Total	246,900
Tax Credit Carryforward, Amount	$ 11,500
Open Tax Year	2015 2016 2017 2018 2019
State and Local Jurisdiction [Member]
Operating Loss Carryforwards, Total	$ 160,500
Tax Credit Carryforward, Amount	$ 31,600
Open Tax Year	2014 2015 2016 2017 2018 2019
Foreign Tax Authority [Member]
Operating Loss Carryforwards, Total	$ 25,100