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. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Outstanding, beginning of year, units (in shares)	334	403	376
Outstanding, beginning of year, wt. avg. (in dollars per share)	$ 14.31	$ 11.04	$ 10.80
Granted, units (in shares)	89	185	222
Granted, wt. avg. (in dollars per share)	$ 24.32	$ 17.60	$ 11.38
Released, units (in shares)	(41)	(186)	(172)
Released, wt. avg. (in dollars per share)	$ 9.92	$ 11.35	$ 11.27
Cancelled, units (in shares)	(42)	(68)	(23)
Cancelled, wt. avg. (in dollars per share)	$ 10.69	$ 11.94	$ 8.75
Outstanding, end of year, units (in shares)	340	334	403
Outstanding, end of year, wt. avg. (in dollars per share)	$ 17.89	$ 14.31	$ 11.04