Financial Information by Segment & Geographic Area - Financial Information by Reportable Segment (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting Information [Line Items]
Revenues from external customers	$ 723	$ 705	$ 678	$ 611	$ 619	$ 621	$ 568	$ 603	$ 2,717	$ 2,411	$ 2,871
Depreciation and amortization									155	161	183
Equity in earnings of affiliated companies									7	3	4
Income (loss) from continuing operations before income taxes									288	194	(377)
Assets	3,314				3,035				3,314	3,035	3,063
Total expenditures for additions to long-lived assets									147	112	141
Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues from external customers									2,611	2,310	2,772
Depreciation and amortization									156	164	184
Equity in earnings of affiliated companies									12	8	9
Income (loss) from continuing operations before income taxes									409	370	332
Assets	2,778				2,597				2,778	2,597	2,753
Total expenditures for additions to long-lived assets									139	110	137
Unallocated and Other [Member]
Segment Reporting Information [Line Items]
Revenues from external customers									106	101	99
Depreciation and amortization									(1)	(3)	(1)
Equity in earnings of affiliated companies									(5)	(5)	(5)
Income (loss) from continuing operations before income taxes									(121)	(176)	(709)
Assets	536				438				536	438	310
Total expenditures for additions to long-lived assets									8	2	4
Reinforcement Materials [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues from external customers									1,381	1,108	1,507
Depreciation and amortization									69	74	83
Equity in earnings of affiliated companies									6		2
Income (loss) from continuing operations before income taxes									193	137	143
Assets	1,189				1,093				1,189	1,093	1,220
Total expenditures for additions to long-lived assets									68	46	44
Performance Chemicals [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues from external customers									908	865	927
Depreciation and amortization									46	48	54
Equity in earnings of affiliated companies										1	1
Income (loss) from continuing operations before income taxes									201	225	178
Assets	708				629				708	629	625
Total expenditures for additions to long-lived assets									47	33	29
Purification Solutions [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues from external customers									281	290	296
Depreciation and amortization									39	39	45
Equity in earnings of affiliated companies									6	7	6
Income (loss) from continuing operations before income taxes									6	(5)	5
Assets	741				736				741	736	789
Total expenditures for additions to long-lived assets									19	30	48
Specialty Fluids [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues from external customers									41	47	42
Depreciation and amortization									2	3	2
Income (loss) from continuing operations before income taxes									9	13	6
Assets	$ 140				$ 139				140	139	119
Total expenditures for additions to long-lived assets									$ 5	$ 1	$ 16