Condensed Consolidated Statements of Comprehensive Income (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Condensed Consolidated Statements of Comprehensive Income [Abstract]
Net sales	$ 104,519	$ 111,307
Cost of products sold (exclusive of depreciation and amortization shown separately below)	82,969	90,299
Selling, general and administrative	8,068	7,966
Depreciation and amortization	4,457	4,035
Gain on disposal of assets	(8)	(1)
Gain from deconsolidation of a bankrupt subsidiary		(209)
Income from operations	9,033	9,217
Interest expense	1,211	1,224
Other expense, net	438	1,036
Income before provision for income taxes	7,384	6,957
Provision for income taxes	1,475	1,450
Net income	5,909	5,507
Other comprehensive income:
Foreign currency translation gain	3,394	6,530
Comprehensive income	$ 9,303	$ 12,037
Basic income per common share:	$ 0.35	$ 0.33
Weighted average shares outstanding	16,961	16,664
Diluted income per common share:	$ 0.35	$ 0.33
Weighted average shares outstanding	17,075	16,910