Financial Information by Segment - Financial Information by Reportable Segment (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Revenues from external customers	$ 812	$ 898
Income (loss) from continuing operations before taxes	51	109
Unallocated and Other [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	31	28
Income (loss) from continuing operations before taxes	(46)	(5)
Reinforcement Materials [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	460	533
Income (loss) from continuing operations before taxes	53	73
Performance Chemicals [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	229	237
Income (loss) from continuing operations before taxes	39	37
Purification Solutions [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	76	72
Income (loss) from continuing operations before taxes	(1)	(9)
Specialty Fluids [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	16	28
Income (loss) from continuing operations before taxes	6	13
Segment Total [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	781	870
Income (loss) from continuing operations before taxes	$ 97	$ 114