Reportable Segment Information - Summary of Financial Information for Each Reportable Segment (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019	Sep. 30, 2019
Segment Reporting Information [Line Items]
Sales		$ 610	$ 667	$ 1,143	$ 1,243
OPERATING INCOME (LOSS)		(468)	44	(451)	37
DEPRECIATION EXPENSE		40	61	80	120
AMORTIZATION EXPENSE		21	21	42	43
EBITDA	[1],[2]	(407)	126	(329)	200
TOTAL ASSETS		6,968		6,968		$ 7,251
Life Sciences [Member]
Segment Reporting Information [Line Items]
Sales		184	196	340	366
OPERATING INCOME (LOSS)		36	33	58	56
DEPRECIATION EXPENSE		8	8	16	16
AMORTIZATION EXPENSE		7	7	14	14
EBITDA	[1],[2]	51	48	88	86
TOTAL ASSETS		1,973		1,973		1,946
Personal Care & Household [Member]
Segment Reporting Information [Line Items]
Sales		159	183	296	337
OPERATING INCOME (LOSS)		(336)	25	(326)	42
DEPRECIATION EXPENSE		10	10	20	21
AMORTIZATION EXPENSE		9	9	18	18
EBITDA	[1],[2]	(317)	44	(288)	81
TOTAL ASSETS		1,019		1,019		1,366
Consumer Specialties [Member]
Segment Reporting Information [Line Items]
Sales		343	379	636	703
OPERATING INCOME (LOSS)		(300)	58	(268)	98
DEPRECIATION EXPENSE		18	18	36	37
AMORTIZATION EXPENSE		16	16	32	32
EBITDA	[1],[2]	(266)	92	(200)	167
TOTAL ASSETS		2,992		2,992		3,312
Specialty Additives [Member]
Segment Reporting Information [Line Items]
Sales		155	169	294	316
OPERATING INCOME (LOSS)		(161)	(2)	(152)	(24)
DEPRECIATION EXPENSE		16	36	32	69
AMORTIZATION EXPENSE		4	3	8	9
EBITDA	[1],[2]	(141)	37	(112)	54
TOTAL ASSETS		1,627		1,627		1,775
Performance Adhesives [Member]
Segment Reporting Information [Line Items]
Sales		85	89	159	171
OPERATING INCOME (LOSS)		16	17	27	26
DEPRECIATION EXPENSE		3	3	6	6
AMORTIZATION EXPENSE		1	1	1	1
EBITDA	[1],[2]	20	21	34	33
TOTAL ASSETS		613		613		618
Industrial Specialties [Member]
Segment Reporting Information [Line Items]
Sales		240	258	453	487
OPERATING INCOME (LOSS)		(145)	15	(125)	2
DEPRECIATION EXPENSE		19	39	38	75
AMORTIZATION EXPENSE		5	4	9	10
EBITDA	[1],[2]	(121)	58	(78)	87
TOTAL ASSETS		2,240		2,240		2,393
Intermediates and Solvents [Member]
Segment Reporting Information [Line Items]
Sales		37	44	64	77
OPERATING INCOME (LOSS)		(2)	9	(14)	11
DEPRECIATION EXPENSE		3	2	6	5
AMORTIZATION EXPENSE			1	1	1
EBITDA	[1],[2]	1	12	(7)	17
TOTAL ASSETS		176		176		185
Intermediates and Solvents [Member] | Intersegment Eliminations
Segment Reporting Information [Line Items]
Sales	[3]	(10)	(14)	(10)	(24)
Unallocated and Other [Member]
Segment Reporting Information [Line Items]
OPERATING INCOME (LOSS)		(21)	(38)	(44)	(74)
DEPRECIATION EXPENSE			2		3
EBITDA	[1],[2]	(21)	$ (36)	(44)	$ (71)
TOTAL ASSETS		$ 1,560		$ 1,560		$ 1,361

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

[2] Includes $20 million of accelerated depreciation for the three months ended March 31, 2019 and $39 million for the six months ended March 31, 2019.

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