Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Statement [Abstract]
Net sales	$ 1,273,078	$ 1,526,730	$ 1,302,314
Cost of sales	1,074,295	1,311,409	1,079,666
Gross margin	198,783	215,321	222,648
Selling, general and administrative expense	133,893	131,388	126,477
Research and development expense	12,505	11,081	7,113
Derivative financial instruments ineffectiveness	0	0	598
Other - net	15,609	15,774	14,827
Operating profit	36,776	57,078	73,633
Interest expense - net	3,134	2,812	2,665
Income before income taxes	33,642	54,266	70,968
Income tax expense	8,978	14,287	24,541
Net income	$ 24,664	$ 39,979	$ 46,427
Basic earnings per share:
Net income per share of common stock	$ 1.21	$ 1.96	$ 2.29
Diluted earnings per share:
Net income per share of common stock	$ 1.19	$ 1.93	$ 2.25
Cash dividends per share	$ 0.225	$ 0	$ 0
Weighted-average number of shares of common stock outstanding
Basic (in shares)	20,418	20,365	20,282
Diluted (in shares)	20,679	20,754	20,590