Note 6 - Employee Stock Benefit Plans - Stock Option Activity Under Share-based Compensation Plans (Details) - $ / shares	12 Months Ended
	Dec. 30, 2017	Dec. 31, 2016	Dec. 26, 2015
Outstanding, beginning of year (in shares)	1,641,000	1,965,000	2,435,000
Outstanding, beginning of year (in dollars per share)	$ 10.79	$ 11.25	$ 11.67
Granted (in shares)	0	0	10,000
Granted (in dollars per share)			$ 10.98
Exercised (in shares)	(1,164,000)	(101,000)	(175,000)
Exercised (in dollars per share)	$ 10.98	$ 7.89	$ 8.65
Cancelled (in shares)	(5,000)	(223,000)	(305,000)
Cancelled (in dollars per share)	$ 20.73	$ 16.19	$ 16.07
Outstanding, end of year (in shares)	472,000	1,641,000	1,965,000
Outstanding, end of year (in dollars per share)	$ 10.20	$ 10.79	$ 11.25
Options exercisable at year end (in shares)	469,000	1,537,000	1,673,000
Options exercisable at year end (in dollars per share)	$ 10.20	$ 10.85	$ 11.47