Commitments, Contingencies and Other Matters (Narrative) (Detail) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2016 USD ($) Entity	Jun. 30, 2009 USD ($)	Jun. 30, 2016 USD ($)
Commitments and Contingencies Disclosure [Line Items]
Environmental remediation charge	$ 170
Pulvair Site Group
Commitments and Contingencies Disclosure [Line Items]
Loss contingency, damages sought	1,700
Arsynco, Inc
Commitments and Contingencies Disclosure [Line Items]
Accrual for environmental loss contingencies	10,035		$ 12,532
Arsynco, Inc | Minimum
Commitments and Contingencies Disclosure [Line Items]
Site contingency loss exposure not accrued	19,700
Arsynco, Inc | Maximum
Commitments and Contingencies Disclosure [Line Items]
Site contingency loss exposure not accrued	21,500
Arsynco, Inc | Selling, General and Administrative Expenses
Commitments and Contingencies Disclosure [Line Items]
Environmental remediation charge	170
BASF Corporation
Commitments and Contingencies Disclosure [Line Items]
Partial reimbursement of environmental remediation costs previously expensed		$ 550
Gain related to partial reimbursement		550
Environmental remediation costs expensed in prior years		$ 1,200
Future remediation costs receivable	4,515		$ 5,639
Subsidiary
Commitments and Contingencies Disclosure [Line Items]
Amount expected to be paid for product registrations and various task force groups	$ 1,826
Berry's Creek Study Area | Arsynco, Inc
Commitments and Contingencies Disclosure [Line Items]
Number of potentially responsible parties | Entity	150