Note 10 - Income Taxes (Details Textual) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2020	Sep. 28, 2019	Sep. 26, 2020	Sep. 28, 2019	Dec. 28, 2019
Income Tax Expense (Benefit), Total	$ (655)	$ 1,066	$ 634	$ 1,480
Other Noncurrent Liabilities [Member]
Liability for Uncertainty in Income Taxes, Noncurrent	$ 23,000		$ 23,000		$ 24,600
Domestic Tax Authority [Member]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%	21.00%	21.00%
Foreign Tax Authority [Member] | Office of the Tax Commissioner, Bermuda [Member]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent			0.00%