Consolidated Statements Of Comprehensive Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jul. 01, 2012	Jun. 30, 2013	Jul. 01, 2012
Consolidated Statements Of Comprehensive Income [Abstract]
Net sales	$ 101,396	$ 117,114	$ 184,586	$ 213,887
Cost of sales	82,985	97,520	149,966	173,941
Gross profit	18,411	19,594	34,620	39,946
Selling and general expenses	5,592	6,268	11,443	12,130
Operating profit	12,819	13,326	23,177	27,816
Other income	147	237	355	498
Earnings before provision for income taxes	12,966	13,563	23,532	28,314
Income tax provision	4,665	4,860	8,377	10,267
Net earnings	8,301	8,703	15,155	18,047
Weighted average common shares outstanding:
Basic and diluted	6,905	6,889	6,904	6,886
Net earnings per share:
Basic and diluted	$ 1.20	$ 1.26	$ 2.20	$ 2.62
Other comprehensive loss, net of tax:
Unrealized loss on available-for-sale securities	28	18	20	14
Comprehensive income	$ 8,273	$ 8,685	$ 15,135	$ 18,033
Cash dividends declared and paid per common share	$ 0.00	$ 0.00	$ 0.00	$ 6.00