Financial Information by Segment - Financial Information by Reportable Segment (Detail) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Revenues from external customers	$ 727	$ 821
Income (loss) from continuing operations before income taxes	50	70
Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	680	772
Income (loss) from continuing operations before income taxes	86	105
Unallocated and Other [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	47	49
Income (loss) from continuing operations before income taxes	(36)	(35)
Reinforcement Materials [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	379	457
Income (loss) from continuing operations before income taxes	47	62
Performance Chemicals [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	242	231
Income (loss) from continuing operations before income taxes	41	36
Purification Solutions [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	59	65
Income (loss) from continuing operations before income taxes	$ (2)	(3)
Specialty Fluids [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues from external customers		19
Income (loss) from continuing operations before income taxes		$ 10