Reportable Segment Information - Summary of Financial Information for Each Reportable Segment (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022	Sep. 30, 2022
Segment Reporting Information [Line Items]
SALES		$ 603	$ 604	$ 1,128	$ 1,115
OPERATING INCOME (LOSS)		83	100	120	142
DEPRECIATION EXPENSE		37	37	74	74
AMORTIZATION EXPENSE		23	24	46	47
EBITDA	[1]	143	161	240	263
TOTAL ASSETS		6,183		6,183		$ 6,213
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
SALES	[2]	(16)	(20)	(33)	(34)
Life Sciences [Member]
Segment Reporting Information [Line Items]
SALES		240	204	447	374
OPERATING INCOME (LOSS)		58	43	92	64
DEPRECIATION EXPENSE		10	8	20	16
AMORTIZATION EXPENSE		7	7	14	14
EBITDA	[1]	75	58	126	94
TOTAL ASSETS		1,964		1,964		1,905
Personal Care [Member]
Segment Reporting Information [Line Items]
SALES		167	172	305	318
OPERATING INCOME (LOSS)		14	28	25	42
DEPRECIATION EXPENSE		10	9	20	18
AMORTIZATION EXPENSE		11	12	22	24
EBITDA	[1]	35	49	67	84
TOTAL ASSETS		1,079		1,079		1,073
Specialty Additives [Member]
Segment Reporting Information [Line Items]
SALES		161	182	304	338
OPERATING INCOME (LOSS)		15	26	16	44
DEPRECIATION EXPENSE		14	17	28	33
AMORTIZATION EXPENSE		5	5	9	9
EBITDA	[1]	34	48	53	86
TOTAL ASSETS		1,664		1,664		1,567
Intermediates [Member]
Segment Reporting Information [Line Items]
SALES		51	66	105	119
OPERATING INCOME (LOSS)		17	27	37	42
DEPRECIATION EXPENSE		3	3	6	7
AMORTIZATION EXPENSE		0	0	1	0
EBITDA	[1]	20	30	44	49
TOTAL ASSETS		172		172		170
Unallocated and Other [Member]
Segment Reporting Information [Line Items]
OPERATING INCOME (LOSS)		(21)	(24)	(50)	(50)
EBITDA	[1]	(21)	$ (24)	(50)	$ (50)
TOTAL ASSETS		$ 1,304		$ 1,304		$ 1,498

[1] Excludes income (loss) from discontinued operations and other net periodic benefit loss (income). See the Statement of Consolidated Comprehensive Income (Loss) for applicable amounts excluded.

[2] Intersegment sales from Intermediates are accounted for at prices that approximate fair value. All other intersegment sales are accounted for at cost.