Note 6 - Employee Benefit Plans - Performance Based Stock Unit Activity Under Share-based Compensation Plans (Details) - Equity Based Performance Stock Units [Member] - $ / shares shares in Thousands	12 Months Ended
	Dec. 28, 2019	Dec. 29, 2018	Dec. 30, 2017
Outstanding, beginning of year, units (in shares)	340	334	403
Outstanding, beginning of year, wt. avg. (in dollars per share)	$ 17.89	$ 14.31	$ 11.04
Granted, units (in shares)	167	89	185
Granted, wt. avg. (in dollars per share)	$ 14.11	$ 24.32	$ 17.60
Released, units (in shares)	(36)	(41)	(186)
Released, wt. avg. (in dollars per share)	$ 11.35	$ 9.92	$ 11.35
Cancelled, units (in shares)	(107)	(42)	(68)
Cancelled, wt. avg. (in dollars per share)	$ 11.35	$ 10.69	$ 11.94
Outstanding, end of year, units (in shares)	364	340	334
Outstanding, end of year, wt. avg. (in dollars per share)	$ 18.72	$ 17.89	$ 14.31