Schedule of Deferred Tax Assets (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010
Deferred tax assets:
Inventory	$ 11,459	$ 9,183
Pension obligations	10,755	22,270
Environmental remediation reserves	7,533	9,997
Accrued expenses	4,314	3,824
Deferred gain on sale of business	996	1,448
Tax credits and carryforwards	515	66
Other	1,117	1,439
Subtotal	36,689	48,227
Valuation allowance		(66)	(10,486)	(66)
Deferred tax assets	36,689	48,161
Deferred tax liabilities:
Property, plant and equipment	(13,358)	(13,805)
Prepaid expenses	(576)	(432)
Other	(95)	(100)
Deferred tax liabilities	(14,029)	(14,337)
Net deferred tax assets	$ 22,660	$ 33,824