Note 8 - Income Taxes - Reconciliation of Income Tax Computed at U.S. Federal Statutory Tax Rate to Provision (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 28, 2019	Dec. 29, 2018	Dec. 30, 2017
Tax provision at U.S. 21% statutory rate (35% in 2017)	$ (15,136)	$ (6,702)	$ 12,378
Impact of Tax Act, before reduction in valuation allowance		5,095	12,397
State income taxes, net of federal tax benefit	(1,097)	(663)	56
Settlements, adjustments and releases from statute expirations	(1,204)	(783)	(1,731)
Federal tax credits	(1,458)	(864)	(371)
Stock-based compensation	587	(838)	(2,801)
Executive compensation limited by Section 162(m)	190	3,456	246
Change in valuation allowance	11,270	(2,015)	(13,484)
Non-deductible transaction related costs		1,106	331
GILTI	2,480	3,531
Foreign rate differential	187	(435)	(4,866)
Other, net	1,099	(257)	89
	$ (3,082)	$ 631	$ 2,244

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