Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Net sales and other operating revenues	$ 3,931	$ 4,321	$ 3,409
Cost of sales	3,092	3,436	2,610
Gross profit	839	885	799
Selling and administrative expenses	253	258	289
Research and technical expenses	57	55	56
Loss on sale of business and asset impairment charge	3	207
Gain on bargain purchase of a business (Note C)		(24)
Income (loss) from operations	526	389	454
Interest and dividend income	31	11	8
Interest expense	(90)	(56)	(49)
Other income (expense)	(16)	(9)	(7)
Income (loss) from operations before income taxes and equity in earnings of affiliated companies	451	335	406
(Provision) benefit for income taxes	28	(102)	(123)
Equity in earnings of affiliated companies, net of tax	5	10	3
Net income (loss)	484	243	286
Net income (loss) attributable to noncontrolling interests, net of tax of $9, $8 and $10	39	34	36
Net income (loss) attributable to Cabot Corporation	$ 445	$ 209	$ 250
Weighted-average common shares outstanding:
Basic	56.1	56.5	56.7
Diluted	56.5	56.9	56.8
Earnings (loss) per common share:
Basic	$ 7.79	$ 3.65	$ 4.35
Diluted	$ 7.73	$ 3.62	$ 4.34
Purification Solutions [Member]
Loss on sale of business and asset impairment charge		$ 197