Note 5 - Income Taxes (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016	Dec. 26, 2015
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		35.00%	35.00%	35.00%
Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Amount		$ 16,600
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability		(4,000)
Deferred Tax Assets, Valuation Allowance		31,491	$ 44,731
Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Portion Held for Repatriation, Amount		2,000
Income Tax Credits and Adjustments		200	200	$ 400
Increase (Decrease) of Net Income Due to Impact of Tax Holidays		$ 2,800	$ 1,000	$ 800
Increase (Decrease) of Earning Per Share Due To Impact Of Tax Holidays		$ 0.10	$ 0.04	$ 0.03
Unrecognized Tax Benefits that Would Impact Effective Tax Rate		$ 4,300	$ 5,200
Decrease in Unrecognized Tax Benefits is Reasonably Possible		600
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued		1,100	$ 1,200
Unrecognized Tax Benefits, Interest Expense, Net of Accrued Interest Reversed		$ (300)		$ 100
Minimum [Member]
Collection Term Range		4 years
Maximum [Member]
Collection Term Range		10 years
Domestic Tax Authority [Member]
Operating Loss Carryforwards		$ 31,200
Tax Credit Carryforward, Amount		$ 7,600
Domestic Tax Authority [Member] | Earliest Tax Year [Member]
Open Tax Year		2013
State and Local Jurisdiction [Member]
Operating Loss Carryforwards		$ 19,000
Tax Credit Carryforward, Amount		$ 14,100
State and Local Jurisdiction [Member] | Earliest Tax Year [Member]
Open Tax Year		2012
Scenario, Forecast [Member]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%