Condensed Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Income Statement [Abstract]
Net sales	$ 69,938	$ 69,956	$ 139,562	$ 143,561
Operating costs and expenses:
Costs of products sold (excluding depreciation)	55,310	54,302	110,400	110,538
Selling and administrative	9,298	9,973	19,156	20,400
Depreciation	2,914	2,754	5,885	5,579
Loss (gain) on disposition of assets	25	(1)	19	(1)
Total operating expenses	67,547	67,028	135,460	136,516
Income from operations	2,391	2,928	4,102	7,045
Other income (expense):
Investment-related income	11	18	24	34
Interest expense	(68)	(61)	(121)	(116)
Other - net	(403)	(226)	(1,007)	(463)
Total other income (expense)	(460)	(269)	(1,104)	(545)
Income before income taxes and equity losses in Chinese joint venture	1,931	2,659	2,998	6,500
Income tax provision	(581)	(770)	(901)	(2,145)
Equity losses in Chinese joint venture	(244)	(381)	(865)	(847)
Net income	$ 1,106	$ 1,508	$ 1,232	$ 3,508
Net income per common share:
Basic	$ 0.11	$ 0.15	$ 0.12	$ 0.34
Diluted	$ 0.11	$ 0.15	$ 0.12	$ 0.34
Cash dividends declared per share	$ 0.18	$ 0.18	$ 0.36	$ 0.36
Weighted average number of common shares outstanding:
Basic	10,357	10,339	10,351	10,334
Diluted	10,407	10,387	10,403	10,390