Reconciliation of Actual Income Tax Expenses (Benefits) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Income Tax Disclosure [Abstract]
Provision for U.S. federal income tax at statutory rate	$ 18,740	$ 35,382	$ 18,153
Effect of foreign income taxes	(629)	130	(140)
Manufacturers’/producers’ deduction	(1,496)	(3,048)	(1,868)
Research and experimentation tax credits	(208)	(661)	(99)
State income taxes, net of federal income tax benefit	45	81	240
Nondeductible expenses	205	253	165
Resolution of prior years’ tax matters	20	(467)	544
Contingency for uncertainty in income taxes		(51)	(335)
Other items	(45)	(83)	84
Income tax expense	$ 16,632	$ 31,536	$ 16,744
Effective tax rate	31.10%	31.20%	32.30%