Condensed Consolidated Statements Of Operations (USD $)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Condensed Consolidated Statements Of Operations [Abstract]
Net sales	$ 73,605,120	$ 89,068,041
Operating costs and expenses:
Costs of products sold (excluding depreciation)	56,236,453	63,394,143
Selling and administrative	10,427,398	10,881,611
Depreciation	2,824,611	2,663,768
Total operating expenses	69,488,462	76,939,522
Income from operations	4,116,658	12,128,519
Other income (expense):
Investment-related income	16,390	22,544
Interest expense	(56,012)	(76,769)
Other - net	(236,722)	(454,649)
Total other income (expense)	(276,344)	(508,874)
Income before income taxes and equity losses in Chinese joint venture	3,840,314	11,619,645
Income tax provision	(1,375,000)	(3,873,000)
Equity losses in Chinese joint venture	(465,763)	(70,068)
Net income	$ 1,999,551	$ 7,676,577
Net income per common share:
Basic	$ 0.19	$ 0.74
Diluted	$ 0.19	$ 0.74
Cash dividends declared per share	$ 0.18	$ 0.18
Weighted average number of common shares outstanding:
Basic	10,329,000	10,305,156
Diluted	10,393,165	10,366,991