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. 25, 2021	Dec. 26, 2020	Dec. 28, 2019
Outstanding, beginning of year, units (in shares)	425	364	340
Outstanding, beginning of year, wt. avg. (in dollars per share)	$ 15.51	$ 18.72	$ 17.89
Granted, units (in shares)	93	200	167
Granted, wt. avg. (in dollars per share)	$ 51.43	$ 13.18	$ 14.11
Released, units (in shares)	(125)	(39)	(36)
Released, wt. avg. (in dollars per share)	$ 21.77	$ 21.40	$ 11.35
Cancelled, units (in shares)	(9)	(100)	(107)
Cancelled, wt. avg. (in dollars per share)	$ 14.04	$ 20.25	$ 11.35
Outstanding, end of year, units (in shares)	384	425	364
Outstanding, end of year, wt. avg. (in dollars per share)	$ 22.22	$ 15.51	$ 18.72