Consolidated Condensed Statements of Income (Unaudited) (USD $)	3 Months Ended		9 Months Ended
	Oct. 01, 2011	Oct. 02, 2010	Oct. 01, 2011	Oct. 02, 2010
Consolidated Condensed Statements of Income [Abstract]
Net sales	$ 121,637,000	$ 118,280,000	$ 352,007,000	$ 359,025,000
Cost of sales	78,795,000	79,894,000	226,359,000	232,933,000
Gross profit	42,842,000	38,386,000	125,648,000	126,092,000
Selling, general and administrative expenses	22,498,000	19,812,000	67,358,000	61,578,000
Operating income	20,344,000	18,574,000	58,290,000	64,514,000
Interest expense	(98,000)	(9,000)	(293,000)	(133,000)
Interest income	88,000	193,000	377,000	315,000
Income before income taxes	20,334,000	18,758,000	58,374,000	64,696,000
Provision for income taxes	5,830,000	5,670,000	17,722,000	19,965,000
Net income	$ 14,504,000	$ 13,088,000	$ 40,652,000	$ 44,731,000
Earnings per share:
Basic	$ 0.45	$ 0.39	$ 1.25	$ 1.33
Diluted	$ 0.45	$ 0.39	$ 1.25	$ 1.33
Dividends declared per share	$ 0.20	$ 0.19	$ 0.58	$ 0.55