Cabot (CBT) 10-Q 9 Aug 21 2021 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Jun. 30, 2021	Aug. 04, 2021
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Trading Symbol	CBT
Entity Registrant Name	Cabot Corporation
Entity Central Index Key	0000016040
Entity Current Reporting Status	Yes
Current Fiscal Year End Date	--09-30
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		56,723,537
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity File Number	1-5667
Entity Tax Identification Number	04-2271897
Entity Address, Address Line One	Two Seaport Lane
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02210-2019
City Area Code	617
Local Phone Number	345-0100
Security Exchange Name	NYSE
Title of 12(b) Security	Common Stock, $1 par value per share
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Transition Report	false
Entity Interactive Data Current	Yes

Consolidated Statements of Oper

Consolidated Statements of Operations (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Statement [Abstract]
Net sales and other operating revenues	$ 917	$ 518	$ 2,505	$ 1,955
Cost of sales	703	449	1,884	1,592
Gross profit	214	69	621	363
Selling and administrative expenses	68	52	200	230
Research and technical expenses	12	13	41	41
Specialty Fluids loss on sale and asset impairment charge				1
Income (loss) from operations	134	4	380	91
Interest and dividend income	2	1	6	7
Interest expense	(12)	(13)	(37)	(41)
Other income (expense)	(1)	(3)	(9)	(6)
Income (loss) before income taxes and equity in earnings of affiliated companies	123	(11)	340	51
(Provision) benefit for income taxes	(30)	5	(93)	(9)
Equity in earnings of affiliated companies, net of tax	2	1	3	2
Net income (loss)	95	(5)	250	44
Net income (loss) attributable to noncontrolling interests, net of tax	9	1	29	10
Net income (loss) attributable to Cabot Corporation	$ 86	$ (6)	$ 221	$ 34
Weighted-average common shares outstanding:
Basic	56.7	56.5	56.7	56.7
Diluted	57	56.5	56.8	56.7
Earnings (loss) per common share:
Basic	$ 1.48	$ (0.12)	$ 3.85	$ 0.59
Diluted	$ 1.48	$ (0.12)	$ 3.84	$ 0.59

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ 95	$ (5)	$ 250	$ 44
Other comprehensive income (loss), net of tax
Foreign currency translation adjustment, net of tax	71	31	89	(4)
Derivatives: net investment hedges
(Gains) losses reclassified to interest expense, net of tax	(1)	(1)	(4)	(3)
(Gains) losses excluded from effectiveness testing and amortized to interest expense, net of tax			1	1
Pension and other postretirement benefit liability adjustments, net of tax	2	1	6	2
Other comprehensive income (loss)	72	31	92	(4)
Comprehensive income (loss)	167	26	342	40
Net income (loss) attributable to noncontrolling interests, net of tax	9	1	29	10
Foreign currency translation adjustment attributable to noncontrolling interests, net of tax	3	2	8	2
Comprehensive income (loss) attributable to noncontrolling interests, net of tax	12	3	37	12
Comprehensive income (loss) attributable to Cabot Corporation	$ 155	$ 23	$ 305	$ 28

Consolidated Balance Sheets (Un

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions	Jun. 30, 2021	Sep. 30, 2020
Current assets:
Cash and cash equivalents	$ 173	$ 151
Accounts and notes receivable, net of reserve for doubtful accounts of $3 and $2	633	418
Inventories:
Raw materials	141	82
Finished goods	293	225
Other	53	52
Total inventories	487	359
Prepaid expenses and other current assets	77	50
Total current assets	1,370	978
Property, plant and equipment, net	1,359	1,314
Goodwill	142	134
Equity affiliates	41	39
Intangible assets, net	103	103
Deferred income taxes	46	53
Other assets	164	160
Total assets	3,225	2,781
Current liabilities:
Short-term borrowings	59	14
Accounts payable and accrued liabilities	602	488
Income taxes payable	34	20
Current portion of long-term debt	9	7
Total current liabilities	704	529
Long-term debt	1,088	1,094
Deferred income taxes	58	58
Other liabilities	281	286
Contingencies (Note G)
Preferred stock:
Authorized: 2,000,000 shares of $1 par value Issued and Outstanding: None and none
Common stock:
Authorized: 200,000,000 shares of $1 par value, Issued: 56,866,956 and 56,616,030 shares, Outstanding: 56,723,495 and 56,466,638 shares	57	57
Less cost of 143,461 and 149,392 shares of common treasury stock	(4)	(4)
Retained earnings	1,169	989
Accumulated other comprehensive income (loss)	(267)	(351)
Total Cabot Corporation stockholders' equity	955	691
Noncontrolling interests	139	123
Total stockholders' equity	1,094	814
Total liabilities and stockholders' equity	$ 3,225	$ 2,781

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) (Unaudited) - USD ($) $ in Millions	Jun. 30, 2021	Sep. 30, 2020
Statement Of Financial Position [Abstract]
Accounts and notes receivable, reserve for doubtful accounts	$ 3	$ 2
Preferred stock, authorized shares	2,000,000	2,000,000
Preferred stock, par value	$ 1	$ 1
Preferred stock, Issued shares	0	0
Preferred stock, Outstanding shares	0	0
Common stock, authorized shares	200,000,000	200,000,000
Common stock, par value	$ 1	$ 1
Common stock, issued shares	56,866,956	56,616,030
Common stock, outstanding shares	56,723,495	56,466,638
Common treasury stock, shares	143,461	149,392

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash Flows from Operating Activities:
Net income (loss)	$ 250	$ 44
Adjustments to reconcile net income (loss) to cash provided by operating activities:
Depreciation and amortization	117	117
Deferred tax provision (benefit)	4	(20)
Employee benefit plan settlement	7
Equity in earnings of affiliated companies	(3)	(2)
Non-cash compensation	16	5
Other non-cash (income) expense	10	4
Cash dividends received from equity affiliates	2	1
Changes in assets and liabilities:
Accounts and notes receivable	(198)	172
Inventories	(125)	74
Prepaid expenses and other assets	(15)	(25)
Accounts payable and accrued liabilities	97	(68)
Income taxes payable	12	(10)
Other liabilities	(17)	(14)
Cash provided (used) by operating activities	157	278
Cash Flows from Investing Activities:
Additions to property, plant and equipment	(115)	(162)
Cash paid for acquisition of businesses, net of cash acquired of $— and $1		(92)
Other	5	2
Cash provided (used) by investing activities	(110)	(252)
Cash Flows from Financing Activities:
Proceeds from issuance (repayments) of commercial paper, net	46	(20)
Proceeds from long-term debt	150	444
Repayments of long-term debt	(167)	(334)
Purchases of common stock	(2)	(44)
Proceeds from sales of common stock	5	3
Cash dividends paid to noncontrolling interests	(20)	(26)
Cash dividends paid to common stockholders	(60)	(60)
Cash provided (used) by financing activities	(48)	(37)
Effects of exchange rate changes on cash	23	4
Increase (decrease) in cash and cash equivalents	22	(7)
Cash and cash equivalents at beginning of period	151	169
Cash and cash equivalents at end of period	$ 173	$ 162

Consolidated Statements of Ca_2

Consolidated Statements of Cash Flows (Parenthetical) (Unaudited) $ in Millions	9 Months Ended
	Jun. 30, 2020USD ($)
Statement Of Cash Flows [Abstract]
Cash acquired in acquisition of business	$ 1

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Millions	Total	Common Stock, Net of Treasury Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total Cabot Corporation Stockholders' Equity [Member]	Noncontrolling Interests [Member]
Beginning Balance at Sep. 30, 2019	$ 1,134	$ 52		$ 1,337	$ (391)	$ 998	$ 136
Beginning Balance, Shares at Sep. 30, 2019		57,081
Adoption of accounting standards				3	(3)
Net income (loss)	46			41		41	5
Total other comprehensive income (loss)	43				40	40	3
Cash dividends paid, Common stock, per share	(20)			(20)		(20)
Cash dividends declared to noncontrolling interests	(19)						(19)
Issuance of stock under equity compensation plans	1		$ 1			1
Issuance of stock under equity compensation plans, Shares		273
Amortization of share-based compensation	1		1			1
Purchase and retirement of common stock	(34)		(2)	(32)		(34)
Purchase and retirement of common stock, Shares		(699)
Ending Balance at Dec. 31, 2019	1,152	$ 52		1,329	(354)	1,027	125
Ending Balance, Shares at Dec. 31, 2019		56,655
Beginning Balance at Sep. 30, 2019	1,134	$ 52		1,337	(391)	998	136
Beginning Balance, Shares at Sep. 30, 2019		57,081
Net income (loss)	44
Total other comprehensive income (loss)	(4)
Ending Balance at Jun. 30, 2020	1,043	$ 53		1,277	(400)	930	113
Ending Balance, Shares at Jun. 30, 2020		56,460
Beginning Balance at Dec. 31, 2019	1,152	$ 52		1,329	(354)	1,027	125
Beginning Balance, Shares at Dec. 31, 2019		56,655
Net income (loss)	3			(1)		(1)	4
Total other comprehensive income (loss)	(78)				(75)	(75)	(3)
Cash dividends paid, Common stock, per share	(20)			(20)		(20)
Cash dividends declared to noncontrolling interests	(16)						(16)
Issuance of stock under equity compensation plans	2		2			2
Issuance of stock under equity compensation plans, Shares		30
Amortization of share-based compensation	2		2			2
Purchase and retirement of common stock	(10)		(4)	(6)		(10)
Purchase and retirement of common stock, Shares		(241)
Ending Balance at Mar. 31, 2020	1,035	$ 52		1,302	(429)	925	110
Ending Balance, Shares at Mar. 31, 2020		56,444
Net income (loss)	(5)			(6)		(6)	1
Total other comprehensive income (loss)	31				29	29	2
Cash dividends paid, Common stock, per share	(20)			(20)		(20)
Issuance of stock under equity compensation plans		$ 1	(1)
Issuance of stock under equity compensation plans, Shares		18
Amortization of share-based compensation	2		2			2
Purchase and retirement of common stock			(1)	1
Purchase and retirement of common stock, Shares		(2)
Ending Balance at Jun. 30, 2020	1,043	$ 53		1,277	(400)	930	113
Ending Balance, Shares at Jun. 30, 2020		56,460
Beginning Balance at Sep. 30, 2020	814	$ 53		989	(351)	691	123
Beginning Balance, Shares at Sep. 30, 2020		56,467
Net income (loss)	70			60		60	10
Total other comprehensive income (loss)	96				89	89	7
Cash dividends paid, Common stock, per share	(20)			(20)		(20)
Cash dividends declared to noncontrolling interests	(1)						(1)
Issuance of stock under equity compensation plans	1		1			1
Issuance of stock under equity compensation plans, Shares		192
Amortization of share-based compensation	4		4			4
Purchase and retirement of common stock	(2)		(2)			(2)
Purchase and retirement of common stock, Shares		(53)
Amount reclassified to retained earnings in excess of additional paid in capital			(3)	3
Ending Balance at Dec. 31, 2020	962	$ 53		1,032	(262)	823	139
Ending Balance, Shares at Dec. 31, 2020		56,606
Beginning Balance at Sep. 30, 2020	814	$ 53		989	(351)	691	123
Beginning Balance, Shares at Sep. 30, 2020		56,467
Net income (loss)	250
Total other comprehensive income (loss)	92
Ending Balance at Jun. 30, 2021	1,094	$ 53		1,169	(267)	955	139
Ending Balance, Shares at Jun. 30, 2021		56,723
Beginning Balance at Dec. 31, 2020	962	$ 53		1,032	(262)	823	139
Beginning Balance, Shares at Dec. 31, 2020		56,606
Net income (loss)	85			75		75	10
Total other comprehensive income (loss)	(76)				(74)	(74)	(2)
Cash dividends paid, Common stock, per share	(20)			(20)		(20)
Cash dividends declared to noncontrolling interests	(11)						(11)
Issuance of stock under equity compensation plans	1		1			1
Issuance of stock under equity compensation plans, Shares		17
Amortization of share-based compensation	6		6			6
Purchase and retirement of common stock, Shares		(1)
Amount reclassified to retained earnings in excess of additional paid in capital			(7)	7
Ending Balance at Mar. 31, 2021	947	$ 53		1,094	(336)	811	136
Ending Balance, Shares at Mar. 31, 2021		56,622
Net income (loss)	95			86		86	9
Total other comprehensive income (loss)	72				69	69	3
Cash dividends paid, Common stock, per share	(20)			(20)		(20)
Cash dividends declared to noncontrolling interests	(9)						(9)
Issuance of stock under equity compensation plans	3		3			3
Issuance of stock under equity compensation plans, Shares		103
Amortization of share-based compensation	6		6			6
Purchase and retirement of common stock, Shares		(2)
Amount reclassified to retained earnings in excess of additional paid in capital			$ (9)	9
Ending Balance at Jun. 30, 2021	$ 1,094	$ 53		$ 1,169	$ (267)	$ 955	$ 139
Ending Balance, Shares at Jun. 30, 2021		56,723

Consolidated Statements of Ch_2

Consolidated Statements of Changes in Stockholders' Equity (Unaudited) (Parenthetical) - $ / shares	3 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Statement Of Stockholders Equity [Abstract]
Common stock, cash dividends paid, per share	$ 0.35	$ 0.35	$ 0.35	$ 0.35	$ 0.35	$ 0.35

Basis of Presentation

Basis of Presentation	9 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Basis of Presentation	A. Basis of Presentation The consolidated financial statements have been prepared in conformity with accounting policies generally accepted in the United States (“U.S.”) and include the accounts of Cabot Corporation (“Cabot” or the “Company”) and its wholly owned subsidiaries and majority-owned and controlled U.S. and non-U.S. subsidiaries. Additionally, Cabot considers consolidation of entities over which control is achieved through means other than voting rights. Intercompany transactions have been eliminated in consolidation. The unaudited consolidated financial statements have been prepared in accordance with the requirements of Form 10-Q and consequently do not include all disclosures required by Form 10-K. Additional information may be obtained by referring to Cabot’s Annual Report on Form 10-K for its fiscal year ended September 30, 2020 (“2020 10-K”). The financial information submitted herewith is unaudited and reflects all adjustments which are, in the opinion of management, necessary to provide a fair statement of the results for the interim periods ended June 30, 2021 and 2020. All such adjustments are of a normal recurring nature. The results for interim periods are not necessarily indicative of the results to be expected for the fiscal year.

Significant Accounting Policies

Significant Accounting Policies	9 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Significant Accounting Policies	B. Significant Accounting Policies Recently Adopted Accounting Standards In June 2016, the FASB issued a new standard on measurement of credit losses. The standard introduces a new "expected loss" impairment model that applies to most financial assets measured at amortized cost and certain other instruments, including trade and other receivables and other financial assets. Entities are required to estimate expected credit losses over the life of financial assets and record an allowance against the assets’ amortized cost basis to present them at the amount expected to be collected. The Company adopted this standard on October 1, 2020. The adoption of this standard did not materially impact the Company’s consolidated financial statements. Recent Accounting Pronouncements In March 2020, the FASB issued a new standard on Reference Rate Reform, which provides temporary optional expedients and exceptions to the existing guidance on contract modifications and hedge accounting to ease the financial reporting burdens related to the expected market transition from the London Interbank Offered Rate ("LIBOR") and other interbank offered rates to alternative reference rates. The standard was effective upon issuance and may generally be applied through December 31, 2022 to any new or amended contracts, hedging relationships, and other transactions that reference LIBOR. The Company is currently evaluating the timing of adoption and the impact of the adoption of this standard on its consolidated financial statements. In December 2019, the FASB issued a new standard Simplifying the Accounting for Income Taxes. The new guidance simplifies the accounting for income taxes by removing several exceptions in the current standard and adding guidance to reduce complexity in certain areas. The new standard is effective for fiscal years beginning after December 15, 2020 and early adoption is permitted. The Company expects to adopt the standard on October 1, 2021. The Company is currently evaluating the impact of the adoption of this standard on its consolidated financial statements.

Acquisition

Acquisition	9 Months Ended
	Jun. 30, 2021
Business Combinations [Abstract]
Acquisition	C. Acquisition Shenzhen Sanshun Nano New Materials Co., Ltd On April 1, 2020, the Company purchased Shenzhen Sanshun Nano New Materials Co., Ltd (SUSN), a leading carbon nanotube producer, for an estimated purchase price of $100 million, consisting of: (i) cash consideration of $84 million, net of $1 million acquired, (ii) contingent consideration of up to $3 million to be paid over the two-year period ending March 31, 2022 upon the satisfaction of certain milestones, and (iii) assumed debt of $13 million. The debt the Company assumed in the transaction was repaid in June 2020. The operating results of SUSN are included in the results of the Company's Performance Chemicals segment beginning in the third quarter of fiscal 2020.

Employee Benefit Plans

Employee Benefit Plans	9 Months Ended
	Jun. 30, 2021
Compensation And Retirement Disclosure [Abstract]
Employee Benefit Plans	D. Employee Benefit Plans Net periodic defined benefit pension costs include the following: Three Months Ended June 30 2021 2020 Pension Benefits U.S. Foreign U.S. Foreign (In millions) Service cost $ — $ 1 $ — $ 1 Interest cost — — 1 1 Expected return on plan assets — (2 ) (1 ) (2 ) Amortization of prior service cost — 2 — — Amortization of actuarial loss — 1 — 1 Settlement charge — 1 — — Net periodic benefit (credit) cost $ — $ 3 $ — $ 1 Nine Months Ended June 30 2021 2020 Pension Benefits U.S. Foreign U.S. Foreign (In millions) Service cost $ — $ 4 $ 1 $ 4 Interest cost — 2 3 3 Expected return on plan assets — (7 ) (3 ) (7 ) Amortization of prior service cost — 2 — — Amortization of actuarial loss — 2 — 2 Settlement charge 6 1 — — Net periodic benefit (credit) cost $ 6 $ 4 $ 1 $ 2 Other postretirement benefit costs were less than $1 million and $1 million for the three and nine months ended June 30, 2021, respectively. Other postretirement benefit costs were less than $1 million and $1 million for the three and nine months ended June 30, 2020, respectively. U.S. Cash Balance Plan Termination In fiscal 2019, the Company’s Board of Directors approved a resolution to terminate the Company’s U.S. pension plan. In fiscal 2020 and 2021, the pension liability was settled through a combination of lump-sum payments and purchased annuities, neither of which required an additional cash contribution to the plan. In the fourth quarter of fiscal 2020, the Company recognized a settlement charge of $3 million related to lump-sum payments made to participants who elected this option, which was recorded in Other income (expense) in the Consolidated Statements of Operations. In the first quarter of fiscal 2021, the Company recognized an additional $6 million settlement charge in Other income (expense) related to the final asset transfers through purchased annuities.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	9 Months Ended
	Jun. 30, 2021
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	E. Goodwill and Intangible Assets The carrying amount of goodwill attributable to each reportable segment with goodwill balances and the changes in those balances during the nine months ended June 30, 2021 are as follows: Reinforcement Materials Performance Chemicals Total (In millions) Balance at September 30, 2020 $ 46 $ 88 $ 134 Foreign currency impact 3 5 8 Balance at June 30, 2021 $ 49 $ 93 $ 142 The following table provides information regarding the Company’s intangible assets: June 30, 2021 September 30, 2020 Gross Carrying Value Accumulated Amortization Net Intangible Assets Gross Carrying Value Accumulated Amortization Net Intangible Assets (In millions) Intangible assets with finite lives Developed technologies $ 63 $ (11 ) $ 52 $ 60 $ (8 ) $ 52 Trademarks 11 (1 ) 10 11 (1 ) 10 Customer relationships 61 (20 ) 41 56 (15 ) 41 Total intangible assets $ 135 $ (32 ) $ 103 $ 127 $ (24 ) $ 103 Intangible assets are amortized over their estimated useful lives, which range between ten and twenty-five years, with a weighted average amortization period of approximately eighteen years. Amortization expense for each of the three months ended June 30, 2021 and 2020 was $2 million and is included in Cost of sales, Selling and administrative expenses and Research and technical expenses in the Consolidated Statements of Operations. Amortization expense for the nine months ended June 30, 2021 and 2020 was $6 million and $5 million, respectively, and is included in Cost of sales, Selling and administrative expenses and Research and technical expenses in the Consolidated Statements of Operations. Total amortization expense is estimated to be approximately $8 million each year for the next five fiscal years.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	9 Months Ended
	Jun. 30, 2021
Stockholders Equity Note [Abstract]
Accumulated Other Comprehensive Income (Loss)	F. Accumulated Other Comprehensive Income (Loss) Comprehensive income combines net income (loss) and other comprehensive income items, which are reported as components of stockholders’ equity in the accompanying Consolidated Balance Sheets. Changes in each component of AOCI, net of tax, were as follows: Currency Translation Adjustment Pension and Other Postretirement Benefit Liability Adjustments Total (In millions) Balance at September 30, 2020, attributable to Cabot Corporation $ (307 ) $ (44 ) $ (351 ) Other comprehensive income (loss) before reclassifications 94 (1 ) 93 Amounts reclassified from AOCI (1 ) 4 3 Less: Other comprehensive income (loss) attributable to noncontrolling interests 7 — 7 Balance at December 31, 2020, attributable to Cabot Corporation (221 ) (41 ) (262 ) Other comprehensive income (loss) before reclassifications (76 ) 1 (75 ) Amounts reclassified from AOCI (1 ) — (1 ) Less: Other comprehensive income (loss) attributable to noncontrolling interests (2 ) — (2 ) Balance at March 31, 2021, attributable to Cabot Corporation (296 ) (40 ) (336 ) Other comprehensive income (loss) before reclassifications 71 (3 ) 68 Amounts reclassified from AOCI (1 ) 5 4 Less: Other comprehensive income (loss) attributable to noncontrolling interests 3 — 3 Balance at June 30, 2021, attributable to Cabot Corporation $ (229 ) $ (38 ) $ (267 ) The amounts reclassified out of AOCI and into the Consolidated Statements of Operations in each of the three and nine months ended June 30, 2021 and 2020 were as follows: Affected Line Item in the Consolidated Three Months Ended June 30 Nine Months Ended June 30 Statements of Operations 2021 2020 2021 2020 (In millions) Derivatives: net investment hedges (Gains) losses reclassified to interest expense Interest expense (Note L) $ (1 ) $ (2 ) $ (4 ) $ (4 ) (Gains) losses excluded from effectiveness testing and amortized to interest expense Interest expense (Note L) — — 1 1 Pension and other postretirement Amortization of actuarial losses and prior service cost (credit) Net Periodic Benefit Cost (Note D) 3 2 4 3 Settlement charge Net Periodic Benefit Cost (Note D) 1 — 7 — Total before tax 3 — 8 — Tax impact Provision (benefit) for income taxes 1 1 (2 ) 1 Total after tax $ 4 $ 1 $ 6 $ 1

Contingencies

Contingencies	9 Months Ended
	Jun. 30, 2021
Commitments And Contingencies Disclosure [Abstract]
Contingencies	G. Contingencies Respirator Liabilities Cabot has exposure in connection with a safety respiratory products business that a subsidiary acquired from American Optical Corporation (“AO”) in an April 1990 asset purchase transaction. The subsidiary manufactured respirators under the AO brand and disposed of that business in July 1995. In connection with its acquisition of the business, the subsidiary agreed, in certain circumstances, to assume a portion of AO’s liabilities, including costs of legal fees together with amounts paid in settlements and judgments, allocable to AO respiratory products used prior to the 1990 purchase by the Cabot subsidiary. In exchange for the subsidiary’s assumption of certain of AO’s respirator liabilities, AO agreed to provide to the subsidiary the benefits of: (i) AO’s insurance coverage for the period prior to the 1990 acquisition and (ii) a former owner’s indemnity of AO holding it harmless from any liability allocable to AO respiratory products used prior to May 1982. As more fully described in the 2020 10-K, the respirator liabilities generally involve claims for personal injury, including asbestosis, silicosis and coal worker’s pneumoconiosis, allegedly resulting from the use of respirators that are alleged to have been negligently designed and/or labeled. At no time did this respiratory product line represent a significant portion of the respirator market. In addition to Cabot’s subsidiary, other parties are responsible for significant portions of the costs of these respirator liabilities (as defined in the 2020 10-K, the “Payor Group”). On February 28, 2020, Cabot, with certain members of the Payor Group, entered into a settlement agreement resolving a large group of claims, including claims alleging serious injury, brought by coal workers in Kentucky and West Virginia represented by common legal counsel. The Company’s share of this liability was $65.2 million, and during the second quarter of fiscal 2020, Cabot recorded a charge of $50 million for this settlement, which was included in Selling and administrative expenses in the Consolidated Statements of Operations. The Company paid $32.6 million of the settlement during the third quarter of fiscal 2020 and the remaining $32.6 million in the first quarter of fiscal 2021. Cabot has a reserve to cover its expected share of liabilities for pending and future respirator liability claims, which is included in Other liabilities and Accounts payable and accrued liabilities on the Consolidated Balance Sheets. The Company expects these liabilities to be incurred over a number of years. The reserve was $20 million and $24 million as of June 30, 2021 and September 30, 2020, respectively. The Company’s current estimate of the cost of its share of pending and future respirator liability claims is based on facts and circumstances existing at this time, including the number and nature of the remaining claims. Developments that could affect the Company’s estimate include, but are not limited to, (i) changes in the number of pending and future claims, (ii) changes in the rate of dismissals without payment of pending claims, (iii) significant changes in the average cost of resolving claims, including potential settlements of groups of claims, (iv) significant changes in the legal costs of defending these claims, (v) changes in the nature of claims received or changes in our assessment of the viability of these claims, (vi) trial and appellate outcomes, (vii) changes in the law and procedure applicable to these claims, (viii) the financial viability of the parties that contribute to the payment of respirator claims, (ix) exhaustion or changes in the recoverability of the insurance coverage maintained by certain members of the Payor Group, or a change in the availability of the indemnity provided by a former owner of AO, (x) changes in the allocation of costs among the various parties paying legal and settlement costs, and (xi) a determination that the assumptions that were used to estimate Cabot’s share of liability are no longer reasonable. The Company cannot determine the impact of these potential developments on its current estimate of its share of liability for existing and future claims. Because reserves are limited to amounts that are probable and estimable as of a relevant measurement date, and there is inherent difficulty in projecting the impact of potential developments on Cabot’s share of liability for these existing and future claims, the actual amount of these liabilities for pending and future claims could be different than the reserved amount. Brazil Indirect Tax Settlements The Company previously filed claims with the Brazilian tax authorities challenging the calculation of certain indirect taxes related to local social contributions for the years 2012 through 2019. During the third quarter of fiscal 2021, the Brazilian Federal Supreme Court rendered a final unappealable decision that clarified the methodology companies should use in the calculation. As a result of this decision, the Company is entitled to recover credits and associated interest related to the historical periods for overpayment of these indirect taxes to be used to offset future Brazilian tax liabilities. As such, the Company recorded a $12 million benefit during the third quarter of fiscal 2021 of which $9 million, related to the credit recovery was included in Net sales and other operating revenues and $3 million, related to interest income was included in Other income (expense) in the Consolidated Statement of Operations. Other Matters The Company has various other lawsuits, claims and contingent liabilities arising in the ordinary course of its business and with respect to its divested businesses. The Company does not believe that any of these matters will have a material adverse effect on its financial position; however, litigation is inherently unpredictable. Cabot could incur judgments, enter into settlements or revise its expectations regarding the outcome of certain matters, and such developments could have a material impact on its results of operations in the period in which the amounts are accrued or its cash flows in the period in which the amounts are paid.

Income Tax

Income Tax	9 Months Ended
	Jun. 30, 2021
Income Tax Disclosure [Abstract]
Income Tax	H. Income Tax Effective Tax Rate Three Months Ended June 30 Nine Months Ended June 30 2021 2020 2021 2020 (Dollars in millions) (Provision) benefit for income taxes $ (30 ) $ 5 $ (93 ) $ (9 ) Effective tax rate 24 % 51 % 27 % 17 % For the three and nine months ended June 30, 2021, the (Provision) benefit for income taxes included a net discrete tax expense of $1 million and $2 million, respectively. For the three and nine months ended June 30, 2020, the (Provision) benefit for income taxes included a net discrete tax benefit of $2 million and $14 million, respectively. The $14 million benefit was comprised of $8 million related to changes in uncertain tax positions and $6 million related to the impact of tax reform legislation in a foreign jurisdiction. Income tax in Interim Periods The Company records its tax provision or benefit on an interim basis using an estimated annual effective tax rate. This rate is applied to the current period ordinary income or loss to determine the income tax provision or benefit allocated to the interim period. The income tax effects of unusual or infrequent items are excluded from the estimated annual effective tax rate and are recognized in the impacted interim period. Losses from jurisdictions for which no benefit can be recognized are excluded from the overall computations of the estimated annual effective tax rate and a separate estimated annual effective tax rate is computed and applied to ordinary income or loss in the loss jurisdiction. Valuation allowances are provided against the future tax benefits that arise from the deferred tax assets in jurisdictions for which no benefit can be recognized. The estimated annual effective tax rate may be significantly impacted by nondeductible expenses and the Company’s projected earnings mix by tax jurisdiction. Adjustments to the estimated annual effective income tax rate are recognized in the period when such estimates are revised. Uncertainties Ca bot and certain subsidiaries are under audit in a number of jurisdictions. In addition, certain statutes of limitations are scheduled to expire in the near future. It is reasonably possible that a change in the unrecognized tax benefits may also occur within the next twelve months related to the settlement of one or more of these audits or the lapse of applicable statutes of limitations. However, an estimated range of the impact on the unrecognized tax benefits cannot be quantified at this time. Cabot files U.S. federal and state and non-U.S. income tax returns in jurisdictions with varying statutes of limitations. The 2017 through 2019 tax years generally remain subject to examination by the IRS and various tax years from 2005 through 2019 remain subject to examination by the respective state tax authorities. In significant non-U.S. jurisdictions, various tax years from 2003 through 2020 remain subject to examination by their respective tax authorities. During the three and nine months ended June 30, 2021, Cabot released uncertain tax positions of a nil amount and $1 million, respectively, due to the expiration of statutes of limitations in various jurisdictions. During the three and nine months ended June 30, 2020, Cabot released uncertain tax positions of $3 million and $11 million, respectively, due to audit settlements and the expiration of statutes of limitations in various jurisdictions.

Earnings Per Share

Earnings Per Share	9 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
Earnings Per Share	I. Earnings Per Share The following tables summarize the components of the basic and diluted earnings (loss) per common share (“EPS”) computations: Three Months Ended June 30 Nine Months Ended June 30 2021 2020 2021 2020 (In millions, except per share amounts) Basic EPS: Net income (loss) attributable to Cabot Corporation $ 86 $ (6 ) $ 221 $ 34 Less: Dividends and dividend equivalents to participating securities 1 — 1 — Less: Undistributed earnings allocated to participating securities (1) 1 — 2 — Earnings (loss) allocated to common shareholders (numerator) $ 84 $ (6 ) $ 218 $ 34 Weighted average common shares and participating securities outstanding 57.5 57.2 57.4 57.4 Less: Participating securities (1) 0.8 0.7 0.7 0.7 Adjusted weighted average common shares (denominator) 56.7 56.5 56.7 56.7 Earnings (loss) per common share - basic: $ 1.48 $ (0.12 ) $ 3.85 $ 0.59 Diluted EPS: Earnings (loss) allocated to common shareholders $ 84 $ (6 ) $ 218 $ 34 Plus: Earnings allocated to participating securities 1 — 2 — Less: Adjusted earnings allocated to participating securities (2) 1 — 2 — Earnings (loss) allocated to common shareholders (numerator) $ 84 $ (6 ) $ 218 $ 34 Adjusted weighted average common shares outstanding 56.7 56.5 56.7 56.7 Effect of dilutive securities: Common shares issuable (3) 0.3 — 0.1 — Adjusted weighted average common shares (denominator) 57.0 56.5 56.8 56.7 Earnings (loss) per common share - diluted: $ 1.48 $ (0.12 ) $ 3.84 $ 0.59 (1) Participating securities consist of shares underlying all outstanding and achieved performance-based restricted stock units and all unvested time-based restricted stock units. The holders of these units are entitled to receive dividend equivalents payable in cash to the extent dividends are paid on the Company’s outstanding common stock and equal in value to the dividends that would have been paid in respect of the shares underlying such units. Undistributed earnings are the earnings which remain after dividends declared during the period are assumed to be distributed to the common and participating shareholders. Undistributed earnings are allocated to common and participating shareholders on the same basis as dividend distributions. The calculation of undistributed earnings is as follows: Three Months Ended June 30 Nine Months Ended June 30 2021 2020 2021 2020 (In millions) Calculation of undistributed earnings (loss): Net income (loss) attributable to Cabot Corporation $ 86 $ (6 ) $ 221 $ 34 Less: Dividends declared on common stock 20 20 60 60 Less: Dividends declared on participating securities 1 — 1 — Undistributed earnings (loss) $ 65 $ (26 ) $ 160 $ (26 ) Allocation of undistributed earnings (loss): Undistributed earnings (loss) allocated to common shareholders $ 64 $ (26 ) $ 158 $ (26 ) Undistributed earnings allocated to participating shareholders 1 — 2 — Undistributed earnings (loss) $ 65 $ (26 ) $ 160 $ (26 ) (2) Undistributed earnings are adjusted for the assumed distribution of dividends to the dilutive securities, which are described in (3) below, and then reallocated to participating securities. (3) Represents incremental shares of common stock from the (i) assumed exercise of stock options issued under Cabot’s equity incentive plans; and (ii) assumed issuance of shares to employees pursuant to the Company’s Deferred Compensation and Supplemental Retirement Plan. For the three and nine months ended June 30, 2021, 177,673 and 956,695 incremental shares of common stock were excluded from the calculation of diluted earnings per share because the inclusion of these shares would have been antidilutive. For the nine months ended June 30, 2020, 1,223,055 incremental shares of common stock were excluded from the calculation of diluted earnings per share because the inclusion of these shares would have been antidilutive. For the three months ended June 30, 2020, 1,853,427 incremental shares of common stock, which includes shares of participating securities as described in (1) above, were excluded from the calculation of diluted earnings per share because the inclusion of these shares would have been antidilutive due to the Company’s net loss position.

Restructuring

Restructuring	9 Months Ended
	Jun. 30, 2021
Restructuring And Related Activities [Abstract]
Restructuring	J. Restructuring Cabot’s restructuring activities were recorded in the Consolidated Statements of Operations in the three and nine months ended June 30,2021 and 2020 as follows: Three Months Ended June 30 Nine Months Ended June 30 2021 2020 2021 2020 (In millions) Cost of sales $ 2 $ — $ 5 $ 5 Selling and administrative expenses 2 3 2 11 Research and technical expenses — — 1 — Total $ 4 $ 3 $ 8 $ 16 Details of all restructuring activities and the related reserves during the nine months ended June 30, 2021 were as follows: Severance and Employee Benefits Environmental Remediation Non-cash Asset Impairment Other Total (In millions) Reserve at September 30, 2020 $ 5 $ 4 $ — $ — $ 9 Charges (gain) — — 2 1 3 Cost charged against assets — — (2 ) — (2 ) Cash paid (2 ) — — (1 ) (3 ) Reserve at December 31, 2020 3 4 — — 7 Charges (gain) 1 — — — 1 Cash paid (2 ) — — — (2 ) Reserve at March 31, 2021 2 4 — — 6 Charges (gain) 3 — — 1 4 Cash paid (1 ) — — (1 ) (2 ) Reserve at June 30, 2021 $ 4 $ 4 $ — $ — $ 8 Cabot’s severance and employee benefit reserves and other closure related reserves are reflected in Accounts payable and accrued liabilities on the Company’s Consolidated Balance Sheets. Cabot’s environmental remediation reserves related to restructuring activities are reflected in Other liabilities on the Company’s Consolidated Balance Sheets. Reorganization Actions During fiscal 2020 and 2021, the Company has undertaken various actions to enable the Company to perform certain activities more effectively. These actions have primarily consisted of the reorganization of Cabot’s leadership structure, the creation of a Global Business Services function and other functional and operational efficiency initiatives. During the nine months ended June 30, 2020, the Company recorded charges of $15 million and paid cash of $10 million related to these activities. As of June 30, 2021, the Company had recorded total charges of $20 million, of which $17 million was recorded in fiscal 2020, primarily related to severance costs, and also had $3 million of accrued severance charges in the Consolidated Balance Sheets related to these actions. The Company expects to record additional restructuring charges of approximately $2 million throughout the rest of fiscal 2021 and $4 million thereafter, primarily related to severance and site demolition costs associated with the reorganization. As of June 30, 2021, the Company had paid a total of $17 million in cash, of which $13 million was paid in fiscal 2020, and expects to have future cash outlays of approximately $1 million in the remainder of fiscal 2021 and $8 million thereafter related to the reorganization. Purification Solutions Transformation Plan In December 2018, the Company initiated a transformation plan to improve the long‐term performance of the Purification Solutions segment. The purpose of the plan was to focus the business’s product portfolio, optimize its manufacturing assets, and streamline its organizational structure to support the new focus. As of June 30, 2021, the Company had recorded total charges of $15 million for this plan, of which $11 million was recorded in prior fiscal years, primarily related to severance costs, and also had $1 million of accrued severance and other charges in the Consolidated Balance Sheets related to this plan. The Company expects to record additional restructuring charges of $1 million throughout the rest of fiscal 2021 and $1 million thereafter primarily related to decommissioning costs associated with the business’s manufacturing facility in Marshall, Texas. As of June 30, 2021, the Company had paid a total of $11 million in cash for this plan, of which $9 million was paid in prior fiscal years, and expects to have future cash outlays of approximately $2 million in the remainder of fiscal 2021 and $1 million thereafter related to this plan.

Financial Instruments and Fair

Financial Instruments and Fair Value Measurements	9 Months Ended
	Jun. 30, 2021
Fair Value Disclosures [Abstract]
Financial Instruments and Fair Value Measurements	K. Financial Instruments and Fair Value Measurements The FASB authoritative guidance on fair value measurements defines fair value, provides a framework for measuring fair value, and requires certain disclosures about fair value measurements. The required disclosures focus on the inputs used to measure fair value. The guidance establishes the following hierarchy for categorizing these inputs: Level 1 — Quoted market prices in active markets for identical assets or liabilities Level 2 — Significant other observable inputs (e.g., quoted prices for similar items in active markets, quoted prices for identical or similar items in markets that are not active, inputs other than quoted prices that are observable such as interest rate and yield curves, and market-corroborated inputs) Level 3 — Significant unobservable inputs There were no transfers of financial assets or liabilities measured at fair value between Level 1 and Level 2 and there were no Level 3 investments during the first nine months of either fiscal 2021 or 2020. At June 30, 2021 and September 30, 2020, Cabot had derivatives relating to foreign currency risks, including a net investment hedge and forward foreign currency contracts, carried at fair value. At June 30, 2021, the fair value of these derivatives was a net asset of $4 million and was included in Prepaid expenses and other current assets, Accounts payable and accrued liabilities, and Other assets on the Consolidated Balance Sheets. At September 30, 2020, the fair value of these derivatives was a net liability of $1 million and was included in Prepaid expenses and other current assets and Other liabilities on the Consolidated Balance Sheets. These derivatives are classified as Level 2 instruments within the fair value hierarchy as the fair value determination was based on observable inputs. At each of June 30, 2021 and September 30, 2020, the fair value of guaranteed investment contracts, included in Other assets on the Consolidated Balance Sheets was $11 million. Guaranteed investment contracts were classified as Level 2 instruments within the fair value hierarchy as the fair value determination was based on other observable inputs. At June 30, 2021 and September 30, 2020, the fair values of cash and cash equivalents, accounts and notes receivable, accounts payable and accrued liabilities, and short-term borrowings and variable rate debt approximated their carrying values due to the short-term nature of these instruments. The carrying value and fair value of the long-term fixed rate debt were $1.07 billion and $1.14 billion, respectively, as of June 30, 2021, and $1.08 billion and $1.18 billion, respectively, as of September 30, 2020. The fair values of Cabot’s fixed rate long-term debt are estimated based on comparable quoted market prices at the respective period ends. The carrying amounts of Cabot’s floating rate long-term debt and finance and operating lease obligations approximate their fair values. All such measurements are based on observable inputs and are classified as Level 2 within the fair value hierarchy. The valuation technique used is the discounted cash flow model.

Derivatives

Derivatives	9 Months Ended
	Jun. 30, 2021
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Derivatives	L. Derivatives Foreign Currency Risk Management Cabot’s international operations are subject to certain risks, including currency exchange rate fluctuations and government actions. Cabot endeavors to match the currency in which debt is issued to the currency of the Company’s major, stable cash receipts. In some situations, Cabot has issued debt denominated in U.S. dollars and then entered into cross-currency swaps that exchange the dollar principal and interest payments into Euro-denominated principal and interest payments. Additionally, the Company has foreign currency exposure arising from its net investments in foreign operations. Cabot may enter into cross-currency swaps to mitigate the impact of currency rate changes on the Company’s net investments. The Company also has foreign currency exposure arising from the denomination of monetary assets and liabilities in foreign currencies other than the functional currency of a given subsidiary as well as the risk that currency fluctuations could affect the dollar value of future cash flows generated in foreign currencies. Accordingly, Cabot uses short-term forward contracts to minimize the exposure to foreign currency risk. In certain situations where the Company has forecasted purchases under a long-term commitment or forecasted sales denominated in a foreign currency, Cabot may enter into appropriate financial instruments in accordance with the Company’s risk management policy to hedge future cash flow exposures. The following table provides details of the derivatives held as of June 30, 2021 and September 30, 2020 to manage foreign currency risk. Notional Amount Description Borrowing June 30, 2021 September 30, 2020 Hedge Designation Cross-Currency Swaps 3.4% Notes USD 250 million swapped to EUR 223 million USD 250 million swapped to EUR 223 million Net investment Forward Foreign Currency Contracts (1) N/A USD 37 million USD 54 million No designation (1) As of June 3 0 , 202 1 , Cabot’s forward foreign exchange contracts were denominated in Indonesian rupiah and Czech koruna . As of September 30, 2020, Cabot’s forward foreign exchange contracts were denominated in Canadian dollar, Indonesian rupiah and Czech koruna. At both June 30, 2021 and September 30, 2020 the fair value of these derivative instruments were a nominal amount. Accounting for Derivative Instruments and Hedging Activities The Company has cross-currency swaps with a notional amount of $250 million, which are designated as hedges of its net investments in certain Euro-denominated subsidiaries. Cash settlements occur semi-annually on March 15 th th The following table summarizes the impact of the cross-currency swaps to AOCI and the Consolidated Statements of Operations: Three Months Ended June 30 2021 2020 2021 2020 2021 2020 Description Gain/(Loss) Recognized in AOCI (Gain)/Loss Reclassified from AOCI into Interest Expense in the Consolidated Statements of Operations (Gain)/Loss Recognized in Interest Expense in the Consolidated Statements of Operations (Amount Excluded from Effectiveness Testing) (In millions) Cross-currency swaps $ 25 $ 1 $ (1 ) $ (2 ) $ — $ — Nine Months Ended June 30 2021 2020 2021 2020 2021 2020 Description Gain/(Loss) Recognized in AOCI (Gain)/Loss Reclassified from AOCI into Interest Expense in the Consolidated Statements of Operations (Gain)/Loss Recognized in Interest Expense in the Consolidated Statements of Operations (Amount Excluded from Effectiveness Testing) (In millions) Cross-currency swaps $ 7 $ 11 $ (4 ) $ (4 ) $ 1 $ 1

Financial Information by Segmen

Financial Information by Segment	9 Months Ended
	Jun. 30, 2021
Segment Reporting [Abstract]
Financial Information by Segment	M. Financial Information by Segment The Company identifies a business as an operating segment if: (i) it engages in business activities from which it may earn revenues and incur expenses; (ii) its operating results are regularly reviewed by the Chief Operating Decision Maker (“CODM”), who is Cabot’s President and Chief Executive Officer, to make decisions about resources to be allocated to the segment and assess its performance; and (iii) it has available discrete financial information. The Company has determined that all of its businesses are operating segments. The CODM reviews financial information at the operating segment level to allocate resources and to assess the operating results and financial performance for each operating segment. Operating segments are aggregated into a reportable segment if the operating segments are determined to have similar economic characteristics and if the operating segments are similar in the following areas: (i) nature of products and services; (ii) nature of production processes; (iii) type or class of customer for their products and services; (iv) methods used to distribute the products or provide services; and (v) if applicable, the nature of the regulatory environment. The Company has three reportable segments: Reinforcement Materials, Performance Chemicals, and Purification Solutions. The Reinforcement Materials segment consists of the rubber blacks and elastomer composites product lines. The Performance Chemicals segment combines the specialty carbons, fumed metal oxides and aerogel product lines into the Performance Additives business, and combines the specialty compounds and inkjet colorants product lines into the Formulated Solutions business. These businesses are similar in terms of economic characteristics, nature of products, processes, customer class and product distribution methods, and, therefore, have been aggregated into one reportable segment. The net sales from each of these businesses for the three and nine months ended June 30, 2021 and 2020 were as follows: Three Months Ended June 30 Nine Months Ended June 30 2021 2020 2021 2020 (In millions) Performance Additives $ 208 $ 151 $ 595 $ 489 Formulated Solutions 95 69 269 218 Total Performance Chemicals $ 303 $ 220 $ 864 $ 707 The Purification Solutions segment consists of the Company’s activated carbon business. Income (loss) before income taxes (“Segment EBIT”) is presented for each reportable segment in the table below. Segment EBIT excludes Interest expense, general unallocated income (expense), unallocated corporate costs, and certain items, meaning items management does not consider representative of on-going operating segment results. In addition, Segment EBIT includes Equity in earnings of affiliated companies, net of tax, the full operating results of a contractual joint venture in Purification Solutions, royalties, Net income attributable to noncontrolling interests, net of tax, and discounting charges for certain Notes receivable. Financial information by reportable segment is as follows: Reinforcement Materials Performance Chemicals Purification Solutions Segment Total Unallocated and Other (1) Consolidated Total (In millions) Three Months Ended June 30, 2021 Revenues from external customers (2) $ 479 $ 303 $ 69 $ 851 $ 66 $ 917 Income (loss) before income taxes (3) $ 85 $ 54 $ 6 $ 145 $ (22 ) $ 123 Three Months Ended June 30, 2020 Revenues from external customers (2) $ 197 $ 220 $ 63 $ 480 $ 38 $ 518 Income (loss) before income taxes (3) $ (5 ) $ 21 $ 2 $ 18 $ (29 ) $ (11 ) Nine Months Ended June 30, 2021 Revenues from external customers (2) $ 1,288 $ 864 $ 191 $ 2,343 $ 162 $ 2,505 Income (loss) before income taxes (3) $ 262 $ 166 $ 6 $ 434 $ (94 ) $ 340 Nine Months Ended June 30, 2020 Revenues from external customers (2) $ 931 $ 707 $ 186 $ 1,824 $ 131 $ 1,955 Income (loss) before income taxes (3) $ 103 $ 93 $ 3 $ 199 $ (148 ) $ 51 ( 1 ) ( 2 ) Consolidated Total Revenues from external customers reconciles to Net sales and other operating revenues on the Consolidated Statements of Operations. Three Months Ended June 30 Nine Months Ended June 30 2021 2020 2021 2020 (In millions) Shipping and handling fees $ 41 $ 22 $ 112 $ 83 By-product sales 19 12 54 46 Other 6 4 (4 ) 2 Total $ 66 $ 38 $ 162 $ 131 ( 3 ) Consolidated Total Income (loss) before income taxes Three Months Ended June 30 Nine Months Ended June 30 2021 2020 2021 2020 (In millions) Interest expense $ (12 ) $ (13 ) $ (37 ) $ (41 ) Certain items (a) Indirect tax settlement credits (Note G) 12 — 12 3 Global restructuring activities (Note J) (4 ) (3 ) (8 ) (16 ) Employee benefit plan settlement and other charges (Note D) (1 ) (2 ) (6 ) (5 ) Acquisition and integration-related charges (2 ) (1 ) (4 ) (3 ) Legal and environmental matters and reserves — (1 ) — (51 ) Specialty Fluids loss on sale and asset impairment charges — — — (1 ) Other — — (1 ) (1 ) Total certain items, pre-tax 5 (7 ) (7 ) (74 ) Unallocated corporate costs (b) (14 ) (10 ) (43 ) (32 ) General unallocated income (expense) (c) 1 2 (4 ) 1 Less: Equity in earnings of affiliated companies, net of tax (d) 2 1 3 2 Total $ (22 ) $ (29 ) $ (94 ) $ (148 ) (a) Certain items are (b) Unallocated corporate costs are costs that are not controlled by the segments and primarily benefit corporate interests. (c) General unallocated income (expense) consists of gains (losses) arising from foreign currency transactions, net of other foreign currency risk management activities, Interest and dividend income, the profit or loss related to the corporate adjustment for unearned revenue, the impact of including the full operating results of a contractual joint venture in Purification Solutions Segment EBIT and unrealized holding gains (losses) for equity securities. (d) Equity in earnings of affiliated companies, net of tax, is included in Segment EBIT and is removed in Unallocated and other to reconcile to Income (loss) from operations before income taxes and equity in earnings from affiliated companies. The Company’s segments operate globally. In addition to presenting Revenue from external customers by reportable segment, the following tables further disaggregate Revenues from external customers by geographic region. Three Months Ended June 30, 2021 Reinforcement Materials Performance Chemicals Purification Solutions Consolidated Total (In millions) Americas $ 189 $ 85 $ 28 $ 302 Asia Pacific 197 118 9 324 Europe, Middle East and Africa 93 100 32 225 Segment revenues from external customers 479 303 69 851 Unallocated and other 66 Net sales and other operating revenues $ 917 Three Months Ended June 30, 2020 Reinforcement Materials Performance Chemicals Purification Solutions Consolidated Total (In millions) Americas $ 59 $ 54 $ 28 $ 141 Asia Pacific 106 98 8 212 Europe, Middle East and Africa 32 68 27 127 Segment revenues from external customers 197 220 63 480 Unallocated and other 38 Net sales and other operating revenues $ 518 Nine Months Ended June 30, 2021 Reinforcement Materials Performance Chemicals Purification Solutions Consolidated Total (In millions) Americas $ 501 $ 232 $ 79 $ 812 Asia Pacific 537 358 27 922 Europe, Middle East and Africa 250 274 85 609 Segment revenues from external customers 1,288 864 191 2,343 Unallocated and other 162 Net sales and other operating revenues $ 2,505 Nine Months Ended June 30, 2020 Reinforcement Materials Performance Chemicals Purification Solutions Consolidated Total (In millions) Americas $ 354 $ 206 $ 83 $ 643 Asia Pacific 398 271 26 695 Europe, Middle East and Africa 179 230 77 486 Segment revenues from external customers 931 707 186 1,824 Unallocated and other 131 Net sales and other operating revenues $ 1,955

Subsequent Events

Subsequent Events	9 Months Ended
	Jun. 30, 2021
Subsequent Events [Abstract]
Subsequent Events	N. Subsequent Events In July 2021, the Company’s Specialty Compounds manufacturing and research and development facility in Pepinster, Belgium experienced significant flooding. The Company continues to assess the impact of the flooding on ongoing operations at the plant and is working with its insurance carriers to assess the amount of damage to equipment and inventory. It is anticipated that the plant will not be able to produce product for at least the remainder of fiscal year 2021. The Company currently estimates that a charge for the damages will be in a range of $10 million to $15 million. The Company anticipates that it may be able to recover a substantial portion of the losses from insurance proceeds, however, the amount and timing of any insurance recovery is not certain at this time. Effective August 6, 2021, the Company entered into a new corporate revolving credit agreement (the “2021 Credit Agreement”), and terminated its existing corporate revolving credit agreement, which was scheduled to mature on October 23, 2022. The borrowing capacity under the 2021 Credit Agreement, which matures on August 6, 2026, subject to two one-year

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	9 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Recently Adopted Accounting Standards	Recently Adopted Accounting Standards In June 2016, the FASB issued a new standard on measurement of credit losses. The standard introduces a new "expected loss" impairment model that applies to most financial assets measured at amortized cost and certain other instruments, including trade and other receivables and other financial assets. Entities are required to estimate expected credit losses over the life of financial assets and record an allowance against the assets’ amortized cost basis to present them at the amount expected to be collected. The Company adopted this standard on October 1, 2020. The adoption of this standard did not materially impact the Company’s consolidated financial statements.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In March 2020, the FASB issued a new standard on Reference Rate Reform, which provides temporary optional expedients and exceptions to the existing guidance on contract modifications and hedge accounting to ease the financial reporting burdens related to the expected market transition from the London Interbank Offered Rate ("LIBOR") and other interbank offered rates to alternative reference rates. The standard was effective upon issuance and may generally be applied through December 31, 2022 to any new or amended contracts, hedging relationships, and other transactions that reference LIBOR. The Company is currently evaluating the timing of adoption and the impact of the adoption of this standard on its consolidated financial statements. In December 2019, the FASB issued a new standard Simplifying the Accounting for Income Taxes. The new guidance simplifies the accounting for income taxes by removing several exceptions in the current standard and adding guidance to reduce complexity in certain areas. The new standard is effective for fiscal years beginning after December 15, 2020 and early adoption is permitted. The Company expects to adopt the standard on October 1, 2021. The Company is currently evaluating the impact of the adoption of this standard on its consolidated financial statements.

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	9 Months Ended
	Jun. 30, 2021
Compensation And Retirement Disclosure [Abstract]
Net Periodic Defined Benefit Pension Costs	Net periodic defined benefit pension costs include the following: Three Months Ended June 30 2021 2020 Pension Benefits U.S. Foreign U.S. Foreign (In millions) Service cost $ — $ 1 $ — $ 1 Interest cost — — 1 1 Expected return on plan assets — (2 ) (1 ) (2 ) Amortization of prior service cost — 2 — — Amortization of actuarial loss — 1 — 1 Settlement charge — 1 — — Net periodic benefit (credit) cost $ — $ 3 $ — $ 1 Nine Months Ended June 30 2021 2020 Pension Benefits U.S. Foreign U.S. Foreign (In millions) Service cost $ — $ 4 $ 1 $ 4 Interest cost — 2 3 3 Expected return on plan assets — (7 ) (3 ) (7 ) Amortization of prior service cost — 2 — — Amortization of actuarial loss — 2 — 2 Settlement charge 6 1 — — Net periodic benefit (credit) cost $ 6 $ 4 $ 1 $ 2

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	9 Months Ended
	Jun. 30, 2021
Goodwill And Intangible Assets Disclosure [Abstract]
Schedule of Goodwill Balances	The carrying amount of goodwill attributable to each reportable segment with goodwill balances and the changes in those balances during the nine months ended June 30, 2021 are as follows: Reinforcement Materials Performance Chemicals Total (In millions) Balance at September 30, 2020 $ 46 $ 88 $ 134 Foreign currency impact 3 5 8 Balance at June 30, 2021 $ 49 $ 93 $ 142
Schedule of Intangible Assets	The following table provides information regarding the Company’s intangible assets: June 30, 2021 September 30, 2020 Gross Carrying Value Accumulated Amortization Net Intangible Assets Gross Carrying Value Accumulated Amortization Net Intangible Assets (In millions) Intangible assets with finite lives Developed technologies $ 63 $ (11 ) $ 52 $ 60 $ (8 ) $ 52 Trademarks 11 (1 ) 10 11 (1 ) 10 Customer relationships 61 (20 ) 41 56 (15 ) 41 Total intangible assets $ 135 $ (32 ) $ 103 $ 127 $ (24 ) $ 103

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) (Tables)	9 Months Ended
	Jun. 30, 2021
Equity [Abstract]
Changes in Each Component of AOCI, Net of Tax	Changes in each component of AOCI, net of tax, were as follows: Currency Translation Adjustment Pension and Other Postretirement Benefit Liability Adjustments Total (In millions) Balance at September 30, 2020, attributable to Cabot Corporation $ (307 ) $ (44 ) $ (351 ) Other comprehensive income (loss) before reclassifications 94 (1 ) 93 Amounts reclassified from AOCI (1 ) 4 3 Less: Other comprehensive income (loss) attributable to noncontrolling interests 7 — 7 Balance at December 31, 2020, attributable to Cabot Corporation (221 ) (41 ) (262 ) Other comprehensive income (loss) before reclassifications (76 ) 1 (75 ) Amounts reclassified from AOCI (1 ) — (1 ) Less: Other comprehensive income (loss) attributable to noncontrolling interests (2 ) — (2 ) Balance at March 31, 2021, attributable to Cabot Corporation (296 ) (40 ) (336 ) Other comprehensive income (loss) before reclassifications 71 (3 ) 68 Amounts reclassified from AOCI (1 ) 5 4 Less: Other comprehensive income (loss) attributable to noncontrolling interests 3 — 3 Balance at June 30, 2021, attributable to Cabot Corporation $ (229 ) $ (38 ) $ (267 )
Amounts Reclassified Out of AOCI	The amounts reclassified out of AOCI and into the Consolidated Statements of Operations in each of the three and nine months ended June 30, 2021 and 2020 were as follows: Affected Line Item in the Consolidated Three Months Ended June 30 Nine Months Ended June 30 Statements of Operations 2021 2020 2021 2020 (In millions) Derivatives: net investment hedges (Gains) losses reclassified to interest expense Interest expense (Note L) $ (1 ) $ (2 ) $ (4 ) $ (4 ) (Gains) losses excluded from effectiveness testing and amortized to interest expense Interest expense (Note L) — — 1 1 Pension and other postretirement Amortization of actuarial losses and prior service cost (credit) Net Periodic Benefit Cost (Note D) 3 2 4 3 Settlement charge Net Periodic Benefit Cost (Note D) 1 — 7 — Total before tax 3 — 8 — Tax impact Provision (benefit) for income taxes 1 1 (2 ) 1 Total after tax $ 4 $ 1 $ 6 $ 1

Income Tax (Tables)

Income Tax (Tables)	9 Months Ended
	Jun. 30, 2021
Income Tax Disclosure [Abstract]
Effective Tax Rate	Effective Tax Rate Three Months Ended June 30 Nine Months Ended June 30 2021 2020 2021 2020 (Dollars in millions) (Provision) benefit for income taxes $ (30 ) $ 5 $ (93 ) $ (9 ) Effective tax rate 24 % 51 % 27 % 17 %

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
Components of Basic and Diluted Earnings (Loss) Per Common Share (EPS)	The following tables summarize the components of the basic and diluted earnings (loss) per common share (“EPS”) computations: Three Months Ended June 30 Nine Months Ended June 30 2021 2020 2021 2020 (In millions, except per share amounts) Basic EPS: Net income (loss) attributable to Cabot Corporation $ 86 $ (6 ) $ 221 $ 34 Less: Dividends and dividend equivalents to participating securities 1 — 1 — Less: Undistributed earnings allocated to participating securities (1) 1 — 2 — Earnings (loss) allocated to common shareholders (numerator) $ 84 $ (6 ) $ 218 $ 34 Weighted average common shares and participating securities outstanding 57.5 57.2 57.4 57.4 Less: Participating securities (1) 0.8 0.7 0.7 0.7 Adjusted weighted average common shares (denominator) 56.7 56.5 56.7 56.7 Earnings (loss) per common share - basic: $ 1.48 $ (0.12 ) $ 3.85 $ 0.59 Diluted EPS: Earnings (loss) allocated to common shareholders $ 84 $ (6 ) $ 218 $ 34 Plus: Earnings allocated to participating securities 1 — 2 — Less: Adjusted earnings allocated to participating securities (2) 1 — 2 — Earnings (loss) allocated to common shareholders (numerator) $ 84 $ (6 ) $ 218 $ 34 Adjusted weighted average common shares outstanding 56.7 56.5 56.7 56.7 Effect of dilutive securities: Common shares issuable (3) 0.3 — 0.1 — Adjusted weighted average common shares (denominator) 57.0 56.5 56.8 56.7 Earnings (loss) per common share - diluted: $ 1.48 $ (0.12 ) $ 3.84 $ 0.59 (1) Participating securities consist of shares underlying all outstanding and achieved performance-based restricted stock units and all unvested time-based restricted stock units. The holders of these units are entitled to receive dividend equivalents payable in cash to the extent dividends are paid on the Company’s outstanding common stock and equal in value to the dividends that would have been paid in respect of the shares underlying such units.
Calculation of Undistributed Earnings	Undistributed earnings are the earnings which remain after dividends declared during the period are assumed to be distributed to the common and participating shareholders. Undistributed earnings are allocated to common and participating shareholders on the same basis as dividend distributions. The calculation of undistributed earnings is as follows: Three Months Ended June 30 Nine Months Ended June 30 2021 2020 2021 2020 (In millions) Calculation of undistributed earnings (loss): Net income (loss) attributable to Cabot Corporation $ 86 $ (6 ) $ 221 $ 34 Less: Dividends declared on common stock 20 20 60 60 Less: Dividends declared on participating securities 1 — 1 — Undistributed earnings (loss) $ 65 $ (26 ) $ 160 $ (26 ) Allocation of undistributed earnings (loss): Undistributed earnings (loss) allocated to common shareholders $ 64 $ (26 ) $ 158 $ (26 ) Undistributed earnings allocated to participating shareholders 1 — 2 — Undistributed earnings (loss) $ 65 $ (26 ) $ 160 $ (26 ) (2) Undistributed earnings are adjusted for the assumed distribution of dividends to the dilutive securities, which are described in (3) below, and then reallocated to participating securities. (3) Represents incremental shares of common stock from the (i) assumed exercise of stock options issued under Cabot’s equity incentive plans; and (ii) assumed issuance of shares to employees pursuant to the Company’s Deferred Compensation and Supplemental Retirement Plan. For the three and nine months ended June 30, 2021, 177,673 and 956,695 incremental shares of common stock were excluded from the calculation of diluted earnings per share because the inclusion of these shares would have been antidilutive. For the nine months ended June 30, 2020, 1,223,055 incremental shares of common stock were excluded from the calculation of diluted earnings per share because the inclusion of these shares would have been antidilutive. For the three months ended June 30, 2020, 1,853,427 incremental shares of common stock, which includes shares of participating securities as described in (1) above, were excluded from the calculation of diluted earnings per share because the inclusion of these shares would have been antidilutive due to the Company’s net loss position.

Restructuring (Tables)

Restructuring (Tables)	9 Months Ended
	Jun. 30, 2021
Restructuring And Related Activities [Abstract]
Recorded Restructuring Activities	Cabot’s restructuring activities were recorded in the Consolidated Statements of Operations in the three and nine months ended June 30,2021 and 2020 as follows: Three Months Ended June 30 Nine Months Ended June 30 2021 2020 2021 2020 (In millions) Cost of sales $ 2 $ — $ 5 $ 5 Selling and administrative expenses 2 3 2 11 Research and technical expenses — — 1 — Total $ 4 $ 3 $ 8 $ 16
Restructuring Activities and Related Reserves	Details of all restructuring activities and the related reserves during the nine months ended June 30, 2021 were as follows: Severance and Employee Benefits Environmental Remediation Non-cash Asset Impairment Other Total (In millions) Reserve at September 30, 2020 $ 5 $ 4 $ — $ — $ 9 Charges (gain) — — 2 1 3 Cost charged against assets — — (2 ) — (2 ) Cash paid (2 ) — — (1 ) (3 ) Reserve at December 31, 2020 3 4 — — 7 Charges (gain) 1 — — — 1 Cash paid (2 ) — — — (2 ) Reserve at March 31, 2021 2 4 — — 6 Charges (gain) 3 — — 1 4 Cash paid (1 ) — — (1 ) (2 ) Reserve at June 30, 2021 $ 4 $ 4 $ — $ — $ 8

Derivatives (Tables)

Derivatives (Tables)	9 Months Ended
	Jun. 30, 2021
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Details of Derivatives Held to Manage Foreign Currency Risk	The following table provides details of the derivatives held as of June 30, 2021 and September 30, 2020 to manage foreign currency risk. Notional Amount Description Borrowing June 30, 2021 September 30, 2020 Hedge Designation Cross-Currency Swaps 3.4% Notes USD 250 million swapped to EUR 223 million USD 250 million swapped to EUR 223 million Net investment Forward Foreign Currency Contracts (1) N/A USD 37 million USD 54 million No designation (1) As of June 3 0 , 202 1 , Cabot’s forward foreign exchange contracts were denominated in Indonesian rupiah and Czech koruna . As of September 30, 2020, Cabot’s forward foreign exchange contracts were denominated in Canadian dollar, Indonesian rupiah and Czech koruna. At both June 30, 2021 and September 30, 2020 the fair value of these derivative instruments were a nominal amount.
Summary Impact of Cross-currency Swaps to AOCI and Consolidated Statements of Operations	The following table summarizes the impact of the cross-currency swaps to AOCI and the Consolidated Statements of Operations: Three Months Ended June 30 2021 2020 2021 2020 2021 2020 Description Gain/(Loss) Recognized in AOCI (Gain)/Loss Reclassified from AOCI into Interest Expense in the Consolidated Statements of Operations (Gain)/Loss Recognized in Interest Expense in the Consolidated Statements of Operations (Amount Excluded from Effectiveness Testing) (In millions) Cross-currency swaps $ 25 $ 1 $ (1 ) $ (2 ) $ — $ — Nine Months Ended June 30 2021 2020 2021 2020 2021 2020 Description Gain/(Loss) Recognized in AOCI (Gain)/Loss Reclassified from AOCI into Interest Expense in the Consolidated Statements of Operations (Gain)/Loss Recognized in Interest Expense in the Consolidated Statements of Operations (Amount Excluded from Effectiveness Testing) (In millions) Cross-currency swaps $ 7 $ 11 $ (4 ) $ (4 ) $ 1 $ 1

Financial Information by Segm_2

Financial Information by Segment (Tables)	9 Months Ended
	Jun. 30, 2021
Segment Reporting [Abstract]
Schedule of Performance Segment	The net sales from each of these businesses for the three and nine months ended June 30, 2021 and 2020 were as follows: Three Months Ended June 30 Nine Months Ended June 30 2021 2020 2021 2020 (In millions) Performance Additives $ 208 $ 151 $ 595 $ 489 Formulated Solutions 95 69 269 218 Total Performance Chemicals $ 303 $ 220 $ 864 $ 707
Financial Information by Reportable Segment	Financial information by reportable segment is as follows: Reinforcement Materials Performance Chemicals Purification Solutions Segment Total Unallocated and Other (1) Consolidated Total (In millions) Three Months Ended June 30, 2021 Revenues from external customers (2) $ 479 $ 303 $ 69 $ 851 $ 66 $ 917 Income (loss) before income taxes (3) $ 85 $ 54 $ 6 $ 145 $ (22 ) $ 123 Three Months Ended June 30, 2020 Revenues from external customers (2) $ 197 $ 220 $ 63 $ 480 $ 38 $ 518 Income (loss) before income taxes (3) $ (5 ) $ 21 $ 2 $ 18 $ (29 ) $ (11 ) Nine Months Ended June 30, 2021 Revenues from external customers (2) $ 1,288 $ 864 $ 191 $ 2,343 $ 162 $ 2,505 Income (loss) before income taxes (3) $ 262 $ 166 $ 6 $ 434 $ (94 ) $ 340 Nine Months Ended June 30, 2020 Revenues from external customers (2) $ 931 $ 707 $ 186 $ 1,824 $ 131 $ 1,955 Income (loss) before income taxes (3) $ 103 $ 93 $ 3 $ 199 $ (148 ) $ 51 ( 1 ) ( 2 ) Consolidated Total Revenues from external customers reconciles to Net sales and other operating revenues on the Consolidated Statements of Operations. Three Months Ended June 30 Nine Months Ended June 30 2021 2020 2021 2020 (In millions) Shipping and handling fees $ 41 $ 22 $ 112 $ 83 By-product sales 19 12 54 46 Other 6 4 (4 ) 2 Total $ 66 $ 38 $ 162 $ 131 ( 3 ) Consolidated Total Income (loss) before income taxes Three Months Ended June 30 Nine Months Ended June 30 2021 2020 2021 2020 (In millions) Interest expense $ (12 ) $ (13 ) $ (37 ) $ (41 ) Certain items (a) Indirect tax settlement credits (Note G) 12 — 12 3 Global restructuring activities (Note J) (4 ) (3 ) (8 ) (16 ) Employee benefit plan settlement and other charges (Note D) (1 ) (2 ) (6 ) (5 ) Acquisition and integration-related charges (2 ) (1 ) (4 ) (3 ) Legal and environmental matters and reserves — (1 ) — (51 ) Specialty Fluids loss on sale and asset impairment charges — — — (1 ) Other — — (1 ) (1 ) Total certain items, pre-tax 5 (7 ) (7 ) (74 ) Unallocated corporate costs (b) (14 ) (10 ) (43 ) (32 ) General unallocated income (expense) (c) 1 2 (4 ) 1 Less: Equity in earnings of affiliated companies, net of tax (d) 2 1 3 2 Total $ (22 ) $ (29 ) $ (94 ) $ (148 ) (a) Certain items are (b) Unallocated corporate costs are costs that are not controlled by the segments and primarily benefit corporate interests. (c) General unallocated income (expense) consists of gains (losses) arising from foreign currency transactions, net of other foreign currency risk management activities, Interest and dividend income, the profit or loss related to the corporate adjustment for unearned revenue, the impact of including the full operating results of a contractual joint venture in Purification Solutions Segment EBIT and unrealized holding gains (losses) for equity securities. (d) Equity in earnings of affiliated companies, net of tax, is included in Segment EBIT and is removed in Unallocated and other to reconcile to Income (loss) from operations before income taxes and equity in earnings from affiliated companies.
Revenues from External Customers by Geographic Region	The Company’s segments operate globally. In addition to presenting Revenue from external customers by reportable segment, the following tables further disaggregate Revenues from external customers by geographic region. Three Months Ended June 30, 2021 Reinforcement Materials Performance Chemicals Purification Solutions Consolidated Total (In millions) Americas $ 189 $ 85 $ 28 $ 302 Asia Pacific 197 118 9 324 Europe, Middle East and Africa 93 100 32 225 Segment revenues from external customers 479 303 69 851 Unallocated and other 66 Net sales and other operating revenues $ 917 Three Months Ended June 30, 2020 Reinforcement Materials Performance Chemicals Purification Solutions Consolidated Total (In millions) Americas $ 59 $ 54 $ 28 $ 141 Asia Pacific 106 98 8 212 Europe, Middle East and Africa 32 68 27 127 Segment revenues from external customers 197 220 63 480 Unallocated and other 38 Net sales and other operating revenues $ 518 Nine Months Ended June 30, 2021 Reinforcement Materials Performance Chemicals Purification Solutions Consolidated Total (In millions) Americas $ 501 $ 232 $ 79 $ 812 Asia Pacific 537 358 27 922 Europe, Middle East and Africa 250 274 85 609 Segment revenues from external customers 1,288 864 191 2,343 Unallocated and other 162 Net sales and other operating revenues $ 2,505 Nine Months Ended June 30, 2020 Reinforcement Materials Performance Chemicals Purification Solutions Consolidated Total (In millions) Americas $ 354 $ 206 $ 83 $ 643 Asia Pacific 398 271 26 695 Europe, Middle East and Africa 179 230 77 486 Segment revenues from external customers 931 707 186 1,824 Unallocated and other 131 Net sales and other operating revenues $ 1,955

Acquisition - Additional Inform

Acquisition - Additional Information (Detail) - USD ($)	Apr. 01, 2020	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Business Acquisition [Line Items]
Businesses acquisition, net of cash acquired				$ 92,000,000
Assumed debt repaid			$ 167,000,000	$ 334,000,000
Shenzhen Sanshun Nano New Materials Co., Ltd [Member]
Business Acquisition [Line Items]
Business acquisition, purchase price	$ 100,000,000
Business acquisition, cash consideration	84,000,000
Businesses acquisition, net of cash acquired	1,000,000
Business acquisition, assumed debt	13,000,000
Assumed debt repaid		$ 13,000,000
Shenzhen Sanshun Nano New Materials Co., Ltd [Member] | Maximum [Member]
Business Acquisition [Line Items]
Business combination future contingent consideration milestone payment	$ 3,000,000

Employee Benefit Plans - Net Pe

Employee Benefit Plans - Net Periodic Defined Benefit Pension Costs (Detail) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Jun. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
U.S. Defined Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Settlement charge		$ 6	$ 3
Pension Benefits [Member] | U.S. Defined Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost						$ 1
Interest cost				$ 1		3
Expected return on plan assets				(1)		(3)
Settlement charge					$ 6
Net periodic benefit (credit) cost					6	1
Pension Benefits [Member] | Foreign Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1			1	4	4
Interest cost				1	2	3
Expected return on plan assets	(2)			(2)	(7)	(7)
Amortization of prior service cost	2				2
Amortization of actuarial loss	1			1	2	2
Settlement charge	1				1
Net periodic benefit (credit) cost	$ 3			$ 1	$ 4	$ 2

Employee Benefit Plans - Additi

Employee Benefit Plans - Additional Information (Detail) - USD ($)	3 Months Ended				9 Months Ended
	Jun. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Defined Benefit Plan Disclosure [Line Items]
Other postretirement benefit costs (gains)					$ 1,000,000	$ 1,000,000
U.S. Defined Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Settlement charge		$ 6,000,000	$ 3,000,000
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Settlement Gain (Loss), Statement of Income or Comprehensive Income [Extensible List]		Other Income (Expense) [Member]	Other Income (Expense) [Member]
Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Other postretirement benefit costs (gains)	$ 1,000,000			$ 1,000,000

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Schedule of Goodwill Balances (Detail) $ in Millions	9 Months Ended
	Jun. 30, 2021USD ($)
Goodwill And Intangible Assets [Line Items]
Beginning balance	$ 134
Foreign currency impact	8
Ending balance	142
Reinforcement Materials [Member]
Goodwill And Intangible Assets [Line Items]
Beginning balance	46
Foreign currency impact	3
Ending balance	49
Performance Chemicals [Member]
Goodwill And Intangible Assets [Line Items]
Beginning balance	88
Foreign currency impact	5
Ending balance	$ 93

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Schedule of Intangible Assets (Detail) - USD ($) $ in Millions	Jun. 30, 2021	Sep. 30, 2020
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value, finite lives	$ 135	$ 127
Accumulated Amortization	(32)	(24)
Net Intangible Assets, finite lives	103	103
Developed Technologies [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value, finite lives	63	60
Accumulated Amortization	(11)	(8)
Net Intangible Assets, finite lives	52	52
Trademarks [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value, finite lives	11	11
Accumulated Amortization	(1)	(1)
Net Intangible Assets, finite lives	10	10
Customer Relationships [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value, finite lives	61	56
Accumulated Amortization	(20)	(15)
Net Intangible Assets, finite lives	$ 41	$ 41

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Goodwill And Intangible Assets [Line Items]
Amortization expense estimated for year one	$ 8		$ 8
Amortization expense estimated for year two	8		8
Amortization expense estimated for year three	8		8
Amortization expense estimated for year four	8		8
Amortization expense estimated for year five	8		8
Cost of Sales, Selling and Administrative Expenses and Research and Technical Expenses [Member]
Goodwill And Intangible Assets [Line Items]
Amortization of intangible assets	$ 2	$ 2	$ 6	$ 5
Minimum [Member]
Goodwill And Intangible Assets [Line Items]
Useful life of intangible assets			10 years
Maximum [Member]
Goodwill And Intangible Assets [Line Items]
Useful life of intangible assets			25 years
Weighted Average [Member]
Goodwill And Intangible Assets [Line Items]
Useful life of intangible assets			18 years

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) - Changes in Each Component of AOCI, Net of Tax (Detail) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	$ 947	$ 962	$ 814	$ 1,035	$ 814	$ 1,134
Ending Balance	1,094	947	962	1,043	1,094	1,043
Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(296)	(221)	(307)		(307)
Other comprehensive income (loss) before reclassifications	71	(76)	94
Amounts reclassified from AOCI	(1)	(1)	(1)
Less: Other comprehensive income (loss) attributable to noncontrolling interests	3	(2)	7
Ending Balance	(229)	(296)	(221)		(229)
Pension and Other Postretirement Benefit Liability Adjustments [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(40)	(41)	(44)		(44)
Other comprehensive income (loss) before reclassifications	(3)	1	(1)
Amounts reclassified from AOCI	5		4
Ending Balance	(38)	(40)	(41)		(38)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(336)	(262)	(351)	(429)	(351)	(391)
Other comprehensive income (loss) before reclassifications	68	(75)	93
Amounts reclassified from AOCI	4	(1)	3	1	6	1
Less: Other comprehensive income (loss) attributable to noncontrolling interests	3	(2)	7
Ending Balance	$ (267)	$ (336)	$ (262)	$ (400)	$ (267)	$ (400)

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Income (Loss) - Amounts Reclassified Out of AOCI (Detail) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
(Gains) Losses Reclassified to Interest Expense [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	$ (1)			$ (2)	$ (4)	$ (4)
(Gains) Losses Excluded from Effectiveness Testing and Amortized to Interest Expense [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total before tax					1	1
Amortization of Actuarial Losses and Prior Service Cost (Credit) [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	3			2	4	3
Settlement Charge [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	1				7
Accumulated Other Comprehensive Income (Loss) [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	3				8
Tax impact	1			1	(2)	1
Total after tax	$ 4	$ (1)	$ 3	$ 1	$ 6	$ 1

Contingencies - Additional Info

Contingencies - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020	Sep. 30, 2020
Loss Contingencies [Line Items]
(Provision) benefit for income taxes	$ (30)		$ 5		$ (93)	$ (9)
Respirator Liabilities [Member]
Loss Contingencies [Line Items]
Respirator liability				$ 65.2
Settlement amount			$ 32.6
Description of pending claims					The Company paid $32.6 million of the settlement during the third quarter of fiscal 2020 and the remaining $32.6 million in the first quarter of fiscal 2021.
Respirator reserve	20				$ 20		$ 24
Respirator Liabilities [Member] | Selling and Administrative Expenses [Member]
Loss Contingencies [Line Items]
Respirator charge				$ 50
Respirator Liabilities [Member] | Accounts Payable and Accrued Liabilities [Member]
Loss Contingencies [Line Items]
Settlement amount		$ 32.6
Brazil Indirect Tax Settlements [Member]
Loss Contingencies [Line Items]
(Provision) benefit for income taxes	12
Brazil Indirect Tax Settlements [Member] | Net Sales and Other Operating Revenues [Member]
Loss Contingencies [Line Items]
Income tax credit recovery	9
Brazil Indirect Tax Settlements [Member] | Other Income (Expense) [Member]
Loss Contingencies [Line Items]
Interest income	$ 3

Income Tax - Effective Tax Rate

Income Tax - Effective Tax Rate (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Tax Disclosure [Abstract]
(Provision) benefit for income taxes	$ (30)	$ 5	$ (93)	$ (9)
Effective tax rate	24.00%	51.00%	27.00%	17.00%

Income Tax - Additional Informa

Income Tax - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Taxes [Line Items]
Net discrete tax (benefits) expense related to tax settlements	$ 1	$ (2)	$ 2	$ (14)
Changes in uncertain tax positions				8
Net tax benefit related to result of changes in non-us tax laws				6
Uncertain tax positions from expirations of statute of limitations		$ 3	$ 1	$ 11
Earliest Tax Year [Member] | United States Internal Revenue Service (IRS) [Member]
Income Taxes [Line Items]
Tax years remain subject to examination			2017
Latest Tax Year [Member] | United States Internal Revenue Service (IRS) [Member]
Income Taxes [Line Items]
Tax years remain subject to examination			2019
State Tax Authorities [Member] | Earliest Tax Year [Member]
Income Taxes [Line Items]
Tax years remain subject to examination			2005
State Tax Authorities [Member] | Latest Tax Year [Member]
Income Taxes [Line Items]
Tax years remain subject to examination			2019
Non-U.S. Jurisdictions [Member] | Earliest Tax Year [Member]
Income Taxes [Line Items]
Tax years remain subject to examination			2003
Non-U.S. Jurisdictions [Member] | Latest Tax Year [Member]
Income Taxes [Line Items]
Tax years remain subject to examination			2020

Earnings Per Share - Components

Earnings Per Share - Components of Basic and Diluted Earnings (Loss) Per Common Share (EPS) (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Basic EPS:
Net income (loss) attributable to Cabot Corporation	$ 86	$ (6)	$ 221	$ 34
Less: Dividends and dividend equivalents to participating securities	1		1
Less: Undistributed earnings allocated to participating securities	1		2
Earnings (loss) allocated to common shareholders (numerator)	$ 84	$ (6)	$ 218	$ 34
Weighted average common shares and participating securities outstanding	57.5	57.2	57.4	57.4
Less: Participating securities	0.8	0.7	0.7	0.7
Adjusted weighted average common shares (denominator)	56.7	56.5	56.7	56.7
Earnings (loss) per common share - basic:	$ 1.48	$ (0.12)	$ 3.85	$ 0.59
Diluted EPS:
Earnings (loss) allocated to common shareholders	$ 84	$ (6)	$ 218	$ 34
Plus: Earnings allocated to participating securities	1		2
Less: Adjusted earnings allocated to participating securities	1		2
Earnings (loss) allocated to common shareholders (numerator)	$ 84	$ (6)	$ 218	$ 34
Adjusted weighted average common shares outstanding	56.7	56.5	56.7	56.7
Common shares issuable	0.3		0.1
Adjusted weighted average common shares (denominator)	57	56.5	56.8	56.7
Earnings (loss) per common share - diluted:	$ 1.48	$ (0.12)	$ 3.84	$ 0.59

Earnings Per Share - Calculatio

Earnings Per Share - Calculation of Undistributed Earnings (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Earnings Per Share [Abstract]
Net income (loss) attributable to Cabot Corporation	$ 86	$ (6)	$ 221	$ 34
Less: Dividends declared on common stock	20	20	60	60
Less: Dividends declared on participating securities	1		1
Undistributed earnings (loss)	65	(26)	160	(26)
Undistributed earnings (loss) allocated to common shareholders	64	$ (26)	158	$ (26)
Undistributed earnings allocated to participating shareholders	$ 1		$ 2

Earnings Per Share - Componen_2

Earnings Per Share - Components of Basic and Diluted Earnings (Loss) Per Common Share (EPS) (Parenthetical) (Detail) - shares	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Earnings Per Share [Abstract]
Antidilutive securities excluded from computation of earnings per share	177,673	1,853,427	956,695	1,223,055

Restructuring - Recorded Restru

Restructuring - Recorded Restructuring Activities (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Restructuring Cost And Reserve [Line Items]
Restructuring reserve, period expense	$ 4	$ 3	$ 8	$ 16
Cost of Sales [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring reserve, period expense	2		5	5
Selling and Administrative Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring reserve, period expense	$ 2	$ 3	2	$ 11
Research and Technical Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring reserve, period expense			$ 1

Restructuring - Restructuring A

Restructuring - Restructuring Activities and Related Reserves (Detail) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2021
Restructuring Cost And Reserve [Line Items]
Reserve balance	$ 6	$ 7	$ 9	$ 9
Charges (gain)	4	1	3
Cost charged against assets			(2)
Cash paid	(2)	(2)	(3)
Reserve balance	8	6	7	8
Severance and Employee Benefits [Member]
Restructuring Cost And Reserve [Line Items]
Reserve balance	2	3	5	5
Charges (gain)	3	1
Cash paid	(1)	(2)	(2)
Reserve balance	4	2	3	4
Non-cash Asset Impairment [Member]
Restructuring Cost And Reserve [Line Items]
Charges (gain)			2
Cost charged against assets			(2)
Other [Member]
Restructuring Cost And Reserve [Line Items]
Charges (gain)	1		1
Cash paid	(1)		(1)
Environmental Remediation [Member]
Restructuring Cost And Reserve [Line Items]
Reserve balance	4	4	4	4
Reserve balance	$ 4	$ 4	$ 4	$ 4

Restructuring - Additional Info

Restructuring - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended			9 Months Ended		12 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2021	Jun. 30, 2020	Sep. 30, 2020
Restructuring Cost And Reserve [Line Items]
Restructuring charges	$ 4	$ 1	$ 3
Reorganization Actions [Member]
Restructuring Cost And Reserve [Line Items]
Severance costs				$ 20	$ 15	$ 17
Accrued severance charges	3			3
Restructuring charges expected throughout rest of 2021 related to site demolition costs	2			2
Restructuring charges expected thereafter fiscal year related to severance and site demolition costs	4			4
Restructuring cash payments of fiscal year	17				$ 10	13
Restructuring cash payments through the reminder of fiscal 2021	1
Restructuring future cash payments thereafter fiscal year	8			8
Purification Solutions Transformation Plan [Member]
Restructuring Cost And Reserve [Line Items]
Accrued severance charges	1			1
Restructuring cash payments of fiscal year				11		9
Restructuring cash payments through the reminder of fiscal 2021				2
Restructuring future cash payments thereafter fiscal year	1			1
Restructuring charges				15		$ 11
Purification Solutions Transformation Plan [Member] | Manufacturing Facility [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring charges expected throughout rest of 2021 related to decommissioning costs	1			1
Restructuring charges expected thereafter fiscal year related to decommissioning costs	$ 1			$ 1

Financial Instruments and Fai_2

Financial Instruments and Fair Value Measurements - Additional Information (Detail) - USD ($)	9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Sep. 30, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, liabilities, Level 2 to Level 1 transfers, amount	$ 0	$ 0
Fair value, assets, Level 2 to Level 1 transfers, amount	0	0
Fair value, liabilities, Level 1 to Level 2 transfers, amount	0	0
Fair value, assets, Level 1 to Level 2 transfers, amount	0	0
Fair value, assets, transfers into Level 3, amount	0	0
Fair value, assets, transfers out of Level 3, amount	0	0
Fair value, liabilities, transfers into Level 3, amount	0	0
Fair value, liabilities, transfers out of Level 3, amount	0	$ 0
Fair value of long-term debt	1,140,000,000		$ 1,180,000,000
Fixed Rate Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying value of long-term debt	1,070,000,000		1,080,000,000
Significant Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other assets in the Consolidated Balance Sheets	11,000,000		11,000,000
Significant Observable Inputs (Level 2) [Member] | Foreign Currency Risks [Member] | Prepaid Expenses and Other Current Assets Accounts Payable and Accrued Liabilities and Other Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets (liabilities), at fair Value, net	$ 4,000,000
Significant Observable Inputs (Level 2) [Member] | Foreign Currency Risks [Member] | Prepaid Expenses and Other Current Assets and Other Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets (liabilities), at fair Value, net			$ (1,000,000)

Derivatives - Details of Deriva

Derivatives - Details of Derivatives Held to Manage Foreign Currency Risk (Detail)		Jun. 30, 2021USD ($)	Jun. 30, 2021EUR (€)	Sep. 30, 2020USD ($)	Sep. 30, 2020EUR (€)
Net Investment Hedge [Member] | Cross Currency Swaps [Member]
Derivative [Line Items]
Notional Amount		$ 250,000,000
Net Investment Hedge [Member] | 3.4% Notes [Member] | Cross Currency Swaps [Member]
Derivative [Line Items]
Notional Amount		$ 250,000,000	€ 223,000,000	$ 250,000,000	€ 223,000,000
Net Investment Hedge [Member] | 3.4% Notes [Member] | Fixed Rate Debt [Member] | Cross Currency Swaps [Member]
Derivative [Line Items]
Interest rate on borrowing		3.40%	3.40%	3.40%	3.40%
Not Designated as Hedging Instrument [Member] | Forward Foreign Currency Contracts [Member]
Derivative [Line Items]
Notional Amount	[1]	$ 37,000,000		$ 54,000,000
[1]	As of June 3 0 , 202 1 , Cabot’s forward foreign exchange contracts were denominated in Indonesian rupiah and Czech koruna . As of September 30, 2020, Cabot’s forward foreign exchange contracts were denominated in Canadian dollar, Indonesian rupiah and Czech koruna. At both June 30, 2021 and September 30, 2020 the fair value of these derivative instruments were a nominal amount.

Derivatives - Additional Inform

Derivatives - Additional Information (Detail) - Cross Currency Swaps [Member] - USD ($)	9 Months Ended
	Jun. 30, 2021	Sep. 30, 2020
Derivative [Line Items]
Fair value of swaps, net assets	$ 4,000,000
Fair value of swaps, net liability		$ 1,000,000
Net Investment Hedge [Member]
Derivative [Line Items]
Notional Amount	250,000,000
Cumulative gain (loss) related to swaps	$ 7,000,000	$ 2,000,000
Net Investment Hedge [Member] | Fixed Rate Debt [Member]
Derivative [Line Items]
Derivative Instruments Frequency of Cash Settlements	semi-annually

Derivatives - Summary Impact of

Derivatives - Summary Impact of Cross-currency Swaps to AOCI and Consolidated Statements of Operations (Detail) - Cross Currency Swaps [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Derivative Instruments Gain Loss [Line Items]
Gain/(Loss) Recognized in AOCI	$ 25	$ 1	$ 7	$ 11
(Gain)/Loss Reclassified from AOCI into Interest Expense in the Consolidated Statements of Operations	$ (1)	$ (2)	(4)	(4)
(Gain)/Loss Recognized in Interest Expense in the Consolidated Statements of Operations (Amount Excluded from Effectiveness Testing)			$ 1	$ 1

Financial Information by Segm_3

Financial Information by Segment - Additional Information (Detail)	9 Months Ended
	Jun. 30, 2021Segment
Segment Reporting Information [Line Items]
Number of business reportable segments	3
Performance Chemicals [Member]
Segment Reporting Information [Line Items]
Number of business reportable segments	1

Financial Information by Segm_4

Financial Information by Segment - Schedule of Performance Segment (Detail) - Performance Chemicals [Member] - Operating Segments [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information [Line Items]
Net sales	$ 303	$ 220	$ 864	$ 707
Performance Additives [Member]
Segment Reporting Information [Line Items]
Net sales	208	151	595	489
Formulated Solutions [Member]
Segment Reporting Information [Line Items]
Net sales	$ 95	$ 69	$ 269	$ 218

Financial Information by Segm_5

Financial Information by Segment - Financial Information by Reportable Segment (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information [Line Items]
Revenues from external customers	$ 917	$ 518	$ 2,505	$ 1,955
Income (loss) before income taxes	123	(11)	340	51
Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	851	480	2,343	1,824
Income (loss) before income taxes	145	18	434	199
Unallocated and Other [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	66	38	162	131
Income (loss) before income taxes	(22)	(29)	(94)	(148)
Reinforcement Materials [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	479	197	1,288	931
Income (loss) before income taxes	85	(5)	262	103
Performance Chemicals [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	303	220	864	707
Income (loss) before income taxes	54	21	166	93
Purification Solutions [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	69	63	191	186
Income (loss) before income taxes	$ 6	$ 2	$ 6	$ 3

Financial Information by Segm_6

Financial Information by Segment - Financial Information by Reportable Segment (Parenthetical) (Detail)	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting [Abstract]
Percentage of sale of an equity method affiliate	100.00%	100.00%	100.00%	100.00%

Financial Information by Segm_7

Financial Information by Segment - Sales of Equity Method Affiliate and Discounting Charges for Certain Notes Receivable, by-product Revenue and Indirect Tax Settlement Credits (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information [Line Items]
Revenues from external customers	$ 917	$ 518	$ 2,505	$ 1,955
Unallocated and Other [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	66	38	162	131
Unallocated and Other [Member] | Shipping and Handling Costs [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	41	22	112	83
Unallocated and Other [Member] | By-product Sales [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	19	12	54	46
Unallocated and Other [Member] | Other [Member]
Segment Reporting Information [Line Items]
Revenues from external customers	$ 6	$ 4	$ (4)	$ 2

Financial Information by Segm_8

Financial Information by Segment - Schedule of Income (Loss) from Continuing Operations before Income Taxes and Equity in Earnings of Affiliated Companies for Unallocated and Other (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information [Line Items]
Interest expense	$ (12)	$ (13)	$ (37)	$ (41)
Global restructuring activities	(4)	(3)	(8)	(16)
Unallocated and Other [Member]
Segment Reporting Information [Line Items]
Interest expense	(12)	(13)	(37)	(41)
Unallocated corporate costs	(14)	(10)	(43)	(32)
General unallocated income (expense)	1	2	(4)	1
Less: Equity in earnings of affiliated companies, net of tax	2	1	3	2
Income from continuing operations before income taxes and equity in earnings of affiliated companies	(22)	(29)	(94)	(148)
Certain Items [Member]
Segment Reporting Information [Line Items]
Indirect tax settlement credits	12		12	3
Global restructuring activities	(4)	(3)	(8)	(16)
Employee benefit plan settlement and other charges	(1)	(2)	(6)	(5)
Acquisition and integration-related charges	(2)	(1)	(4)	(3)
Legal and environmental matters and reserves		(1)		(51)
Other			(1)	(1)
Total certain items, pre-tax	$ 5	$ (7)	$ (7)	(74)
Specialty Fluids [Member] | Certain Items [Member]
Segment Reporting Information [Line Items]
Loss on sale and asset impairment charge				$ (1)

Financial Information by Segm_9

Financial Information by Segment - Revenue from External Customers by Geographic Region (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information [Line Items]
Net sales and other operating revenues	$ 917	$ 518	$ 2,505	$ 1,955
Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues	851	480	2,343	1,824
Unallocated and Other [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues	66	38	162	131
Americas [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues	302	141	812	643
Asia Pacific [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues	324	212	922	695
Europe, Middle East and Africa [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues	225	127	609	486
Reinforcement Materials [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues	479	197	1,288	931
Reinforcement Materials [Member] | Americas [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues	189	59	501	354
Reinforcement Materials [Member] | Asia Pacific [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues	197	106	537	398
Reinforcement Materials [Member] | Europe, Middle East and Africa [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues	93	32	250	179
Performance Chemicals [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues	303	220	864	707
Performance Chemicals [Member] | Americas [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues	85	54	232	206
Performance Chemicals [Member] | Asia Pacific [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues	118	98	358	271
Performance Chemicals [Member] | Europe, Middle East and Africa [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues	100	68	274	230
Purification Solutions [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues	69	63	191	186
Purification Solutions [Member] | Americas [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues	28	28	79	83
Purification Solutions [Member] | Asia Pacific [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues	9	8	27	26
Purification Solutions [Member] | Europe, Middle East and Africa [Member]
Segment Reporting Information [Line Items]
Net sales and other operating revenues	$ 32	$ 27	$ 85	$ 77

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - Subsequent Events [Member]	Aug. 06, 2021USD ($)Option	Jul. 31, 2021USD ($)
Revolving Credit Facility, expires fiscal 2023 [Member]
Subsequent Event [Line Items]
Revolving credit facility, borrowing capacity		$ 1,000,000,000
Debt instrument, maturity date		Oct. 23, 2022
Revolving Credit Facility, expires fiscal 2026 [Member]
Subsequent Event [Line Items]
Revolving credit facility, borrowing capacity	$ 1,000,000,000
Debt instrument, maturity date	Aug. 6, 2026
Revolving credit facility, number of options to extend | Option	2
Revolving credit facility, options extension period	1 year
Revolving credit facility, cap amount used to calculate net debt	$ 150,000,000
Maximum [Member] | Revolving Credit Facility, expires fiscal 2026 [Member]
Subsequent Event [Line Items]
Debt instrument, covenant, ratio of consolidated total debt to consolidated EBITDA	3.50%
Flood [Member] | Minimum [Member]
Subsequent Event [Line Items]
Estimated charge for damages		$ 10,000,000
Flood [Member] | Maximum [Member]
Subsequent Event [Line Items]
Estimated charge for damages		$ 15,000,000