Note 8 - Income Taxes (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	35.00%	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	84,718	31,491
Increase (Decrease) of Net Income Due to Impact of Tax Holidays	$ 2,400	$ 2,800	$ 1,000
Increase (Decrease) of Earning Per Share Due To Impact Of Tax Holidays	$ 0.08	$ 0.10	$ 0.04
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	$ 8,200	$ 4,300
Decrease in Unrecognized Tax Benefits is Reasonably Possible	2,700	600
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued, Total	$ 1,500	1,100
Unrecognized Tax Benefits, Interest Expense, Net of Accrued Interest Reversed		$ (300)
Minimum [Member]
Collection Term Range	4 years
Maximum [Member]
Collection Term Range	10 years
Domestic Tax Authority [Member]
Operating Loss Carryforwards, Total	$ 244,200
Tax Credit Carryforward, Amount	$ 13,500
Open Tax Year	2014 2015 2016 2017 2018
State and Local Jurisdiction [Member]
Operating Loss Carryforwards, Total	$ 147,600
Tax Credit Carryforward, Amount	$ 53,500
Open Tax Year	2013 2014 2015 2016 2017 2018
Foreign Tax Authority [Member]
Operating Loss Carryforwards, Total	$ 12,700