Financial Information by Segment - Revenue from External Customers by Geographic Region (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]
Net sales and other operating revenues	$ 968	$ 1,149	$ 2,966	$ 3,209
Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues	931	1,106	2,858	3,089
Unallocated and Other [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues	37	43	108	120
Americas [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues	354	416	1,064	1,124
Asia Pacific [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues	353	412	1,120	1,209
Europe, Middle East and Africa [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues	224	278	674	756
Reinforcement Materials [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues		23	72
Reinforcement Materials [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues	624	730	1,939	1,947
Reinforcement Materials [Member] | Americas [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues	260	302	781	767
Reinforcement Materials [Member] | Asia Pacific [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues	234	265	752	773
Reinforcement Materials [Member] | Europe, Middle East and Africa [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues	130	163	406	407
Performance Chemicals [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues		4	11
Performance Chemicals [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues	307	376	919	1,045
Performance Chemicals [Member] | Americas [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues	94	114	283	314
Performance Chemicals [Member] | Asia Pacific [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues	119	147	368	422
Performance Chemicals [Member] | Europe, Middle East and Africa [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues	$ 94	$ 115	$ 268	309
Purification Solutions [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues				97
Purification Solutions [Member] | Americas [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues				43
Purification Solutions [Member] | Asia Pacific [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues				14
Purification Solutions [Member] | Europe, Middle East and Africa [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues				$ 40