Consolidated Statements of Operations (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Statement [Abstract]
Net sales	$ 281,050	$ 292,905	$ 344,816
Operating costs and expenses:
Costs of products sold (excluding depreciation)	217,342	225,906	256,030
Selling and administrative	39,682	40,530	41,887
Depreciation	11,342	10,661	10,153
Credit for asbestos litigation	(16,340)	(540)	0
Loss on disposition of assets	57	56	272
Total operating expenses	252,083	276,613	308,342
Income from operations	28,967	16,292	36,474
Other income (expense):
Investment-related income	89	63	146
Interest expense	(245)	(246)	(315)
Other - net	(1,631)	(942)	(1,578)
Total other income (expense)	(1,787)	(1,125)	(1,747)
Income before income taxes and equity losses in Chinese joint venture	27,180	15,167	34,727
Income tax provision	(5,813)	(5,218)	(12,916)
Equity losses in Chinese joint venture (including an impairment charge of $6,407 in 2013)	(8,930)	(1,594)	(502)
Net income	$ 12,437	$ 8,355	$ 21,309
Net income per common share:
Basic	$ 1.20	$ 0.81	$ 2.07
Diluted	$ 1.20	$ 0.80	$ 2.05
Weighted average number of common shares outstanding:
Basic	10,358,000	10,338,000	10,319,000
Diluted	10,406,478	10,389,678	10,393,159