Financial Information by Segment - Financial Information by Reportable Segment (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Segment Reporting Information [Line Items]
Revenues from external customers	$ 968	$ 1,149	$ 2,966	$ 3,209
Reinforcement Materials [Member]
Segment Reporting Information [Line Items]
Revenues from external customers		23	72
Performance Chemicals [Member]
Segment Reporting Information [Line Items]
Revenues from external customers		$ 4	$ 11