Reconciliation of Actual Income Tax Expenses (Benefits) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Income Tax Disclosure [Abstract]
Provision (benefit) for U.S. federal income tax at statutory rate	$ (17,442)	$ 18,740	$ 35,382
Effect of foreign income taxes	249	(629)	130
Manufacturers’/producers’ deduction		(1,496)	(3,048)
Research and experimentation tax credits	(400)	(208)	(661)
State income taxes, net of federal income tax benefit	2	45	81
Nondeductible expenses	488	205	253
Resolution of prior years’ tax matters	96	20	(467)
Contingency for uncertainty in income taxes	(121)		(51)
Other items	(65)	(45)	(83)
Income tax expense	$ (17,193)	$ 16,632	$ 31,536
Effective tax rate	(34.50%)	31.10%	31.20%