Note 2 - Correction of Immaterial Errors - Effects of Adjustments to Correct Immaterial Errors, Statements of Equity (Details) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Oct. 01, 2016	Sep. 26, 2015	Jan. 02, 2016	Dec. 27, 2014	Dec. 28, 2013
Scenario, Previously Reported [Member] | Retained Earnings [Member]
Total equity			$ 562,717	$ 523,302	$ 445,059
Scenario, Previously Reported [Member]
Net income			82,466	99,418
Comprehensive income			57,921	57,875
Total equity			744,198	727,665	686,916
Restatement Adjustment [Member] | Retained Earnings [Member]
Total equity			(4,946)	(3,346)	(2,028)
Restatement Adjustment [Member]
Net income			(1,600)	(1,318)
Comprehensive income			(1,600)	(1,318)
Total equity			(4,946)	(3,346)	(2,028)
Retained Earnings [Member]
Total equity			557,771	519,956	443,031
Net income	$ 77,243	$ 60,003	80,866	98,100
Comprehensive income			56,321	56,557
Total equity	$ 803,376		$ 739,252	$ 724,319	$ 684,888