Financial Information by Segment - Financial Information by Reportable Segment (Detail) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Revenues from external customers	$ 965	$ 968
Income (loss) before income taxes	84	(93)
Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	929	930
Income (loss) before income taxes	123	137
Unallocated and Other [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	36	38
Income (loss) before income taxes	(39)	(230)
Reinforcement Materials [Member]
Segment Reporting Information [Line Items]
Revenues from external customers		22
Reinforcement Materials [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	643	563
Income (loss) before income taxes	94	85
Performance Chemicals [Member]
Segment Reporting Information [Line Items]
Revenues from external customers		4
Performance Chemicals [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	286	306
Income (loss) before income taxes	$ 29	52
Purification Solutions [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues from external customers		$ 61