Goodwill and Other Intangible Assets (Schedule of Goodwill Balances) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended								12 Months Ended		12 Months Ended
	Sep. 30, 2012		Sep. 30, 2011	Sep. 30, 2012 Reinforcement Materials [Member]	Sep. 30, 2010 Reinforcement Materials [Member]	Sep. 30, 2012 Performance Materials [Member]	Sep. 30, 2011 Performance Materials [Member]	Sep. 30, 2010 Performance Materials [Member]	Sep. 30, 2011 Advanced Technologies [Member]	Sep. 30, 2012 Advanced Technologies [Member]	Sep. 30, 2012 Purification Solutions [Member]
Goodwill And Other Intangible Asset [Line Items]
Balance at September 30, 2010	$ 40		$ 39	$ 27	$ 27	$ 11	$ 11	$ 11	$ 1	$ 2
Goodwill acquired	432	[1]									432	[1]
Foreign currency translation adjustment and other			1						1
Foreign currency translation adjustment	8			1							7
Balance at September 30, 2011	$ 480		$ 40	$ 28	$ 27	$ 11	$ 11	$ 11	$ 2	$ 2	$ 439

[1] Goodwill acquired relates to the acquisition of Norit in fiscal 2012.