Commitments and Contingencies - Schedule of Raw Material Purchased under Long Term Purchase Agreements (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Raw Material Purchased Under Long Term Purchase Agreements [Line Items]
Raw material purchased	$ 352	$ 432	$ 441
Reinforcement Materials [Member]
Raw Material Purchased Under Long Term Purchase Agreements [Line Items]
Raw material purchased	276	354	371
Performance Chemicals [Member]
Raw Material Purchased Under Long Term Purchase Agreements [Line Items]
Raw material purchased	62	43	34
Purification Solutions [Member]
Raw Material Purchased Under Long Term Purchase Agreements [Line Items]
Raw material purchased	$ 14	32	34
Other [Member]
Raw Material Purchased Under Long Term Purchase Agreements [Line Items]
Raw material purchased		$ 3	$ 2