Financial Information by Segment - Schedule of Performance Segment (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Sales Information [Line Items]
Net sales	$ 812	$ 898
Performance Chemicals [Member] | Operating Segments [Member]
Sales Information [Line Items]
Net sales	229	237
Performance Chemicals [Member] | Specialty Carbons and Formulations [Member] | Operating Segments [Member]
Sales Information [Line Items]
Net sales	157	163
Performance Chemicals [Member] | Metal Oxides [Member] | Operating Segments [Member]
Sales Information [Line Items]
Net sales	$ 72	$ 74