Acquisition of Si En (Schedule of Pro Forma Financial Information) (Details) (Si En, USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
Si En
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net sales	$ 277,792	$ 273,091
Net income (loss)	$ 56,585	$ 45,033
Basic net income (loss) per share (in dollars per share)	$ 2.13	$ 1.76
Diluted net income (loss) per share (in dollars per share)	$ 2.00	$ 1.67