Note 12 - Segment Information (Details) - Net Income, Assets and Certain Other Items of Segments (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 28, 2014	Sep. 29, 2013	Sep. 28, 2014	Sep. 29, 2013
Segment Reporting Information [Line Items]
Sales	$ 188,138	$ 146,623	$ 546,143	$ 448,319
Operating income	12,490	8,975	39,768	32,305
Outside Sales [Member] | Manufacturing [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales	138,512	112,578	410,146	349,068
Outside Sales [Member] | Distribution [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales	49,626	34,045	135,997	99,251
Outside Sales [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales	188,138	146,623	546,143	448,319
Inside Sales [Member] | Manufacturing [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales	4,861	5,302	15,176	15,523
Inside Sales [Member] | Distribution [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales	639	507	1,874	2,119
Inside Sales [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales	5,500	5,809	17,050	17,642
Manufacturing [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating income	13,647	9,333	43,062	34,412
Distribution [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating income	2,673	2,020	7,522	6,292
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating income	$ 16,320	$ 11,353	$ 50,584	$ 40,704