Note 10 - Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended			12 Months Ended
	Oct. 01, 2016	Sep. 26, 2015	Oct. 01, 2016	Oct. 01, 2016	Sep. 26, 2015	Jan. 02, 2016	Dec. 27, 2014
Net income	$ 30,802	$ 11,324	$ 77,243	$ 77,243	$ 60,003	$ 80,866	$ 98,100
Basic (in shares)	22,578	22,581		22,515	22,623
Net effect of dilutive stock options and restricted share units (in shares)	156	112		160	148
Average shares - Diluted (in shares)	22,734	22,693		22,675	22,771
Net income per share (see Note 10):
Net income per share - Basic (in dollars per share)	$ 1.36	$ 0.50		$ 3.43	$ 2.65	$ 3.58	$ 4.35
Net income per share - Diluted (in dollars per share)	$ 1.35	$ 0.50		$ 3.41	$ 2.64	$ 3.56	$ 4.32