Financial Information by Segment - Financial Information by Reportable Segment (Detail) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Revenues from external customers	$ 968	$ 746
Income (loss) before income taxes	(93)	99
Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	904	701
Income (loss) before income taxes	137	140
Unallocated and Other [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	64	45
Income (loss) before income taxes	(230)	(41)
Reinforcement Materials [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	541	375
Income (loss) before income taxes	85	88
Performance Chemicals [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	302	267
Income (loss) before income taxes	52	54
Purification Solutions [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	$ 61	59
Income (loss) before income taxes		$ (2)