Financial Information About Segment Operations (Detail) (USD $) In Thousands, unless otherwise specified	1 Months Ended	12 Months Ended				24 Months Ended
	Jun. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2009	Sep. 30, 2006
Segment Reporting Information [Line Items]
Revenues		$ 185,627	$ 160,714	$ 138,584
Corporate Expenses		(14,326)	(14,124)	(15,847)
Environmental Remediation Charges	(6,000)	(700)	(6,000)		(13,700)	(26,000)
Operating Income (Loss)		28,098	7,885	6,935
Depreciation and amortization		13,700	14,058	14,796
Capital Expenditures:
Capital Expenditures		8,788	11,931	11,744
Assets, at year end:
Assets, at year end		246,464	229,806	245,844
Fine Chemicals
Segment Reporting Information [Line Items]
Revenues		111,536	89,497	69,632
Operating Income (Loss)		8,678	(6,283)	(7,583)
Depreciation and amortization		11,914	12,473	12,997
Capital Expenditures:
Capital Expenditures		7,383	11,153	10,614
Assets, at year end:
Assets, at year end		143,551	144,003	137,252
Specialty Chemicals
Segment Reporting Information [Line Items]
Revenues		68,513	66,905	62,611
Operating Income (Loss)		34,919	35,600	30,571
Depreciation and amortization		1,401	1,136	1,148
Capital Expenditures:
Capital Expenditures		1,353	756	1,047
Assets, at year end:
Assets, at year end		21,029	19,785	39,411
Other Businesses
Segment Reporting Information [Line Items]
Revenues		5,578	4,312	6,341
Operating Income (Loss)		(473)	(1,308)	(206)
Depreciation and amortization		18	17	16
Capital Expenditures:
Capital Expenditures		18	8	12
Assets, at year end:
Assets, at year end		7,302	5,064	4,395
Total Operating Segments
Segment Reporting Information [Line Items]
Operating Income (Loss)		43,124	28,009	22,782
Corporate
Segment Reporting Information [Line Items]
Depreciation and amortization		367	432	635
Corporate Expense [Member]
Capital Expenditures:
Capital Expenditures		34	14	71
Assets, at year end:
Assets, at year end		$ 74,582	$ 60,954	$ 64,786