Commitments and Contingencies - Schedule of Raw Material Purchased under Long Term Purchase Agreements (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Raw Material Purchased Under Long Term Purchase Agreements [Line Items]
Raw material purchased	$ 432	$ 441	$ 370
Reinforcement Materials [Member]
Raw Material Purchased Under Long Term Purchase Agreements [Line Items]
Raw material purchased	354	371	312
Performance Materials [Member]
Raw Material Purchased Under Long Term Purchase Agreements [Line Items]
Raw material purchased	43	34	47
Purification Solutions [Member]
Raw Material Purchased Under Long Term Purchase Agreements [Line Items]
Raw material purchased	32	34	4
Advanced Technologies [Member]
Raw Material Purchased Under Long Term Purchase Agreements [Line Items]
Raw material purchased			6
Other [Member]
Raw Material Purchased Under Long Term Purchase Agreements [Line Items]
Raw material purchased	$ 3	$ 2	$ 1