Financial Information about Segment Operations (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013	Mar. 31, 2012
Segment Reporting Information [Line Items]
Revenues	$ 50,044	$ 39,918	$ 86,362	$ 78,403
Corporate Expenses	(3,890)	(3,167)	(7,976)	(6,793)
Operating Income (Loss)	4,845	4,795	9,793	7,554
Depreciation and amortization	3,104	3,404	6,414	6,777
Fine Chemicals
Segment Reporting Information [Line Items]
Revenues	37,267	20,594	58,614	42,069
Operating Income (Loss)	3,750	(978)	5,027	(2,165)
Depreciation and amortization	2,894	2,928	5,909	5,968
Specialty Chemicals
Segment Reporting Information [Line Items]
Revenues	11,934	18,961	26,284	33,181
Operating Income (Loss)	5,218	9,297	13,135	16,941
Depreciation and amortization	123	377	330	612
Other Businesses
Segment Reporting Information [Line Items]
Revenues	843	363	1,464	3,153
Operating Income (Loss)	(233)	(357)	(393)	(429)
Depreciation and amortization	5	5	10	9
Total Operating Segments
Segment Reporting Information [Line Items]
Operating Income (Loss)	8,735	7,962	17,769	14,347
Corporate
Segment Reporting Information [Line Items]
Depreciation and amortization	$ 82	$ 94	$ 165	$ 188