Acquisition of Norit (Proforma of net sales and results of operations) (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Sep. 30, 2012		Sep. 30, 2011
Business Acquisition Pro Forma Information [Line Items]
Net sales	$ 3,585		$ 3,449
Income from continuing operations	$ 209	[1]	$ 226	[1]
Income from continuing operations per common share:
Basic	$ 3.27		$ 3.47
Diluted	$ 3.23		$ 3.42

[1] Norit recognized a pre-tax gain of approximately $33 million in other income during its year ended December 31, 2011 in connection with a legal settlement.