Condensed Consolidated Statements of Operations (USD $) In Thousands, except Per Share data	3 Months Ended		6 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Net sales	$ 265,514	$ 248,588	$ 555,370	$ 492,382
Operating costs and expenses:
Cost of sales	203,319	178,870	413,823	361,756
Selling, general and administrative expenses	28,355	24,999	58,631	49,214
Research and development	7,362	6,224	14,448	12,255
Restructuring charges	1,605	2,303	2,630	4,095
Net (gain) loss on sales and disposals of assets	(40)	(1,770)	83	(1,435)
Total operating costs and expenses	240,601	210,626	489,615	425,885
Operating income	24,913	37,962	65,755	66,497
Other (income) expense:
Interest income	(31)	(84)	(74)	(105)
Interest expense	7,282	7,334	14,682	14,792
Other (income) expense, net	1,297	(4,792)	1,202	(3,118)
Loss on early extinguishment of debt				38,248
Income before income taxes	16,365	35,504	49,945	16,680
Income tax expense	2,047	593	3,778	1,868
Net income	$ 14,318	$ 34,911	$ 46,167	$ 14,812
Net income per share:
Basic (in dollars per share)	$ 0.32	$ 1.29	$ 1.10	$ 0.55
Diluted (in dollars per share)	$ 0.27	$ 0.68	$ 0.88	$ 0.29
Weighted-average shares outstanding:
Basic (in shares)	44,370	27,092	41,924	27,092
Diluted (in shares)	52,230	51,194	52,307	50,529