0001193125-26-279285 | 11-K | XBRL Viewer

Reconciliation of Financial Statements to Form 5500 - Summary Of a Reconciliation Of Net Assets Available For Benefits (Detail) - EBP 022 [Member] - USD ($)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
EBP, Reconciliation of Financial Statement to Form 5500 [Line Items]
Net assets available for benefits per the financial statements	$ 924,338,139	$ 875,636,357
Deemed distributions -reduction of loans	(83,511)	(80,797)
Net assets available for benefits per Form 5500	924,254,628	$ 875,555,560
Net increase in net assets available for benefits per the financial statements	48,701,782
Deemed distributions -reduction of loans	(2,714)
Net increase in assets available for benefits per Form 5500	$ 48,699,068

- Definition

Amount of asset less liability available to pay benefit of participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)), including, but not limited to, aggregation of participants' individual account balances.

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+ Details

Party-In-Interest - Additional Information (Detail) - EBP 022 [Member] - USD ($)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
EBP, Related Party and Party-in-Interest Transactions [Line Items]
EBP, Investment, excluding plan Interest in master trust, fair value	$ 920,270,423	$ 871,963,904
EBP, Employer, Common Stock [Member]
EBP, Related Party and Party-in-Interest Transactions [Line Items]
EBP, Investment, excluding plan Interest in master trust, fair value	40,128,718	$ 63,319,850
EBP, change in net asset available for benefit, increase from dividend income on investment	$ 1,140,749

- Definition

Fair value of investment, excluding plan interest in master trust, held by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)). Includes, but is not limited to, derivative, investment measured at net asset value per share as practical expedient, and insurance contract not meeting fully-benefit responsive investment criteria.

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+ Details

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2025

EBP 022 [Member]

EBP, Investment, Fair Value and NAV [Line Items]

Summary of Fair Value Hierarchy

The following tables set forth by level and major categorization within the fair value hierarchy, the Plan’s assets at fair value as of December 31:


	2025
	Total		Level 1		Level 2		Level 3
Mutual funds	$	552,163,935	$	552,163,935	$	—	$	—
Company stock*		40,128,718		40,128,718		—		—

Total assets in fair value hierarchy		592,292,653		592,292,653		—		—
Common collective trusts**		327,977,770		—		—		—

Total	$	920,270,423	$	592,292,653	$	—	$	—


	2024
	Total		Level 1		Level 2		Level 3
Mutual funds	$	506,445,493	$	506,445,493	$	—	$	—
Company stock*		63,319,850		63,319,850		—		—

Total assets in fair value hierarchy		569,765,343		569,765,343		—		—
Common collective trusts**		302,198,561		—		—		—

Total	$	871,963,904	$	569,765,343	$	—	$	—

*	Includes both Cabot Common ESOP Stock Fund and Cabot Common Stock Fund.

In accordance with Subtopic

820-10,

certain investments that were measured at NAV per share (or its equivalent) have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the line items presented in the Statement of Net Assets Available for Benefits.

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

Tabular disclosure of fair value of investment held by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)), including, but not limited to, fair value measured at net asset value per share as practical expedient (NAV).

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+ Details

Summary of Significant Accounting Policies (Policies) - EBP 022 [Member]	12 Months Ended
	Dec. 31, 2025
EBP, Description of Plan [Line Items]
Basis of Accounting	Basis of Accounting The accompanying financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”).
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make certain estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of additions and deductions during the reporting period. Actual amounts could differ from those estimates.
Fair Value Measurements	Fair Value Measurements The Plan performs fair value measurements in accordance with Financial Accounting Standards Board (FASB) Accounting Standards Codification 820, Fair Value Measurement (ASC 820). Refer to Note 3 for the fair value measurement disclosures associated with the Plan’s investments.
Investment Valuation	Investment Valuation The Statements of Net Assets Available for Benefits reflect the Plan’s investments at their fair values. Fair value of a financial instrument is the price that would be received on the sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. See Note 3 for a discussion of fair value measurements.
Income Recognition	Income Recognition Purchases and sales of securities are reflected on a trade date basis. Gains or losses on sales of securities are based on average cost. Dividends received in cash are recorded on the ex-dividend date. Dividend payments received in shares of Cabot common stock are recorded on the ex-dividend date in an amount equal to the fair value of the common stock on that date. Interest income is recorded as earned on the accrual basis. The Plan presents in the Statement of Changes in Net Assets Available for Benefits, the net appreciation (depreciation) in the fair value of its investments which consists of (i) realized gains or losses, and (ii) unrealized appreciation (depreciation) on those investments. Management fees and operating expenses related to investments in the mutual funds and common collective trust fund are charged directly to the funds and deducted from income earned on a daily basis by the funds and are not separately reflected in the accompanying financial statements. Consequently, management fees and operating expenses are reflected as a reduction of investment return for such investments.
Notes Receivable from Participants	Notes Receivable from Participants Notes receivable from participants are measured at their unpaid principal balance plus any accrued but unpaid interest. Delinquent participant loans are recorded as distributions based on the terms of the Plan document.
Contributions	Contributions Contributions from plan participants and company contributions are recorded in the year in which the participant contributions are withheld from compensation.
Benefit Payments	Benefit Payments Benefit payments to participants are recorded upon distribution.

Description of the Plan - Additional Information (Detail) - EBP 022 [Member]	12 Months Ended
	Dec. 31, 2025 USD ($) d age
EBP, Description of Plan [Line Items]
Participant contribution, Percentage	50.00%
Participant age, catch-up contribution, Threshold \| age	50
Participant contribution, plan opting decision making, number of days, maximum \| d	60
Participant contribution, automatic, deferral rate	6.00%
Annual increase in deferral rate under auto-escalation	1.00%
Employee benefit plan participant contribution maximum deferral rate	15.00%
Employer contribution, matching percentage	100.00%
Employer contribution, participant compensation matched, percentage	6.00%
Employee benefit plan employer contribution true up matching percentage description	The Plan also provides an employer matching true up contribution at year-end to ensure all participants receive a total match in the amount of the lesser of (1) 100% of the participant’s contribution for the year; or (2) 6% of the participant’s eligible compensation for the year.
Employee benefit plan company retirement contribution (As A percentage of eligible earnings)	4.00%
Employee benefit plan, participant account, vesting percentage	100.00%
Employee benefit plan, company retirement contribution, completion of service, Threshold	2 years
Employee benefit plan, plan termination, participant account, vesting percentage	100.00%
Employee benefit plan, vested account payable, participant age, threshold \| age	65
Employee benefit plan lump sum payment account balance threshold	$ 1,000
Employee benefit plan lump sum payment percentage	100.00%
Investment, Identifier [Axis]: Notes Receivable from Participants
EBP, Description of Plan [Line Items]
Employee benefit plan note receivable from participant account maximum borrowing amount description	Cabot employees may obtain loans from the Plan in an amount not to exceed, in the aggregate, the lesser of $50,000 or 50% of the total vested amount in the participant’s account.
Employee benefit plan loan repayment period maximum	5 years
Employee benefit plan note receivable from participant account borrowing standardize percentage	prime rate plus 2%
Maximum [Member]
EBP, Description of Plan [Line Items]
Employee benefit plan lump sum payment threshold	$ 5,000
EBP, vested amount of direct rollover if no election	$ 5,000
EBP, asset held for investment, participant loan, interest rate	10.50%
Maximum [Member] \| Investment, Identifier [Axis]: Notes Receivable from Participants
EBP, Description of Plan [Line Items]
EBP, asset held for investment, participant loan, interest rate	10.50%
Minimum [Member]
EBP, Description of Plan [Line Items]
Employee benefit plan lump sum payment threshold	$ 1,000
EBP, vested amount of direct rollover if no election	$ 1,000
EBP, asset held for investment, participant loan, interest rate	5.25%
Minimum [Member] \| Investment, Identifier [Axis]: Notes Receivable from Participants
EBP, Description of Plan [Line Items]
EBP, asset held for investment, participant loan, interest rate	5.25%

Fair Value Measurements - Summary of Fair Value Hierarchy (Detail) - EBP 022 [Member] - USD ($)

Dec. 31, 2025

Dec. 31, 2024

EBP, Investment, Fair Value and NAV [Line Items]

Investments, at fair value

$ 920,270,423

$ 871,963,904

Mutual Fund [Member]

EBP, Investment, Fair Value and NAV [Line Items]

Investments, at fair value

552,163,935

506,445,493

Common Stock [Member]

EBP, Investment, Fair Value and NAV [Line Items]

Investments, at fair value

^[1]

40,128,718

63,319,850

Fair Value, Inputs, Level 1 [Member]

EBP, Investment, Fair Value and NAV [Line Items]

Investments, at fair value

592,292,653

569,765,343

Fair Value, Inputs, Level 1 [Member] | Mutual Fund [Member]

EBP, Investment, Fair Value and NAV [Line Items]

Investments, at fair value

552,163,935

506,445,493

Fair Value, Inputs, Level 1 [Member] | Common Stock [Member]

EBP, Investment, Fair Value and NAV [Line Items]

Investments, at fair value

^[1]

40,128,718

63,319,850

Fair Value, Inputs, Level 1 [Member] | Common Collective Trust [Member]

EBP, Investment, Fair Value and NAV [Line Items]

Investments, at fair value

^[2]

Fair Value, Inputs, Level 2 [Member]

EBP, Investment, Fair Value and NAV [Line Items]

Investments, at fair value

Fair Value, Inputs, Level 2 [Member] | Mutual Fund [Member]

EBP, Investment, Fair Value and NAV [Line Items]

Investments, at fair value

Fair Value, Inputs, Level 2 [Member] | Common Stock [Member]

EBP, Investment, Fair Value and NAV [Line Items]

Investments, at fair value

^[1]

Fair Value, Inputs, Level 2 [Member] | Common Collective Trust [Member]

EBP, Investment, Fair Value and NAV [Line Items]

Investments, at fair value

^[2]

Fair Value, Inputs, Level 3 [Member]

EBP, Investment, Fair Value and NAV [Line Items]

Investments, at fair value

Fair Value, Inputs, Level 3 [Member] | Mutual Fund [Member]

EBP, Investment, Fair Value and NAV [Line Items]

Investments, at fair value

Fair Value, Inputs, Level 3 [Member] | Common Stock [Member]

EBP, Investment, Fair Value and NAV [Line Items]

Investments, at fair value

^[1]

Fair Value, Inputs, Level 3 [Member] | Common Collective Trust [Member]

EBP, Investment, Fair Value and NAV [Line Items]

Investments, at fair value

^[2]

Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member]

EBP, Investment, Fair Value and NAV [Line Items]

Investments, at fair value

592,292,653

569,765,343

Fair Value Measured at Net Asset Value Per Share [Member] | Common Collective Trust [Member]

EBP, Investment, Fair Value and NAV [Line Items]

Investments, at fair value

^[2]

$ 327,977,770

$ 302,198,561

[1]	Includes both Cabot Common ESOP Stock Fund and Cabot Common Stock Fund.
[2]	In accordance with Subtopic 820-10, certain investments that were measured at NAV per share (or its equivalent) have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the line items presented in the Statement of Net Assets Available for Benefits.

Statements of Net Assets Available for Benefits - EBP 022 [Member] - USD ($)

Dec. 31, 2025

Dec. 31, 2024

Assets:

Investments, at fair value

$ 920,270,423

$ 871,963,904

Receivables:

Employer contribution receivable

450,000

279,174

Notes receivable from participants

3,617,716

^[1]

3,393,279

Total receivables

4,067,716

3,672,453

Net assets available for benefits

$ 924,338,139

$ 875,636,357

[1]	Indicates party-in-interest to the Plan

Description of the Plan

12 Months Ended

Dec. 31, 2025

EBP 022 [Member]

EBP, Description of Plan [Line Items]

Description of the Plan

1.	Description of the Plan

General

Cabot Corporation (“Cabot” or the “Company”) initially adopted the Cabot Corporation Employee Stock Ownership Plan (the “ESOP”) in 1988, the Cabot Retirement Incentive Savings Plan in 1994 (previously the Cabot Profit-Sharing and Savings Plan, adopted in 1952) (the “CRISP”), and the Cabot Employee Savings Plan in 1987 (the “CESP”). As of December 31, 2000, the CRISP and the CESP were merged with and into the ESOP. The combined amended and restated plan was a defined contribution plan and was renamed the Cabot Retirement Savings Plan, which had two components, a 401(k) plan and an Employee Stock Ownership Plan (“ESOP”). As of December 31, 2013, all shares under the ESOP component of the Plan have been fully allocated and the related debt repaid, and the remaining 401(k) component of the Plan was amended and renamed the Cabot 401(k) Plan (the “Plan”). The Plan is subject to provisions of the Employee Retirement Income Security Act of 1974, as amended (“ERISA”).

The following brief description of the Plan is provided for general information purposes only. Participants should refer to the Plan document for more complete information.

Eligibility

All U.S. employees of the Company and its participating subsidiaries (except certain temporary and leased employees) are eligible to participate in the Plan beginning on the later of the first day of employment or the date the employee is included in an employee group which participates.

Employee Contributions

By means of a salary reduction arrangement, a Cabot participant may make contributions to his or her account. Participants may elect to contribute up to 50% of their U.S. eligible compensation on a

before-tax

basis, an

after-tax

basis, a Roth

after-tax

basis or a combination thereof, subject to certain limitations under the Internal Revenue Code (the “Code”). Participants age 50 and older may make

catch-up

contributions. Participants may also contribute amounts representing distributions from other qualified defined benefit or defined contribution plans. Participants are automatically enrolled in the Plan if they do not make an election to contribute within 60 days of their eligibility to participate. Participants who are automatically enrolled are deemed to have made an election to make

pre-tax

contributions in an amount of 6%

their eligible compensation and to increase this contribution rate by

% of employee eligible compensation each year in January, up to a maximum

deferral

rate of 15%. Participants may choose to opt out or change their contribution rate at any time.

Company Contributions

The Company matching contribution is 100% up to the first 6% of eligible compensation and is made each pay period. The Plan also provides an employer matching true up contribution at

year-end

to ensure all participants receive a total match in the amount of the lesser of (1) 100% of the participant’s contribution for the year; or (2) 6% of the participant’s eligible compensation for the year. In addition to the match, a Company retirement contribution of 4% of eligible earnings is made each pay period. The Company match and Company retirement contributions are invested in accordance with participant allocations.

The Company may make discretionary contributions to participants under the terms of the Plan. No such discretionary contributions were made during the year ended December 31, 2025.

Participant Accounts

Individual accounts are maintained for each Plan participant. Each participant account is credited with the participant’s contribution, Company contributions and Plan earnings, and charged with withdrawals and an allocation of Plan losses. Allocations are based on participant earnings or account balances, as defined in the Plan. The benefit to which a participant is entitled is the benefit that can be provided from the participant’s vested account.

Investments

Participants direct the investment of their contributions into various investment options offered by the Plan including the Cabot Common Stock Fund which consists primarily of Cabot common stock.

Vesting

Each Cabot participant is at all times

100

% vested in his or her contributions. All participants are at all times 100% vested in the Company match and earnings thereon, and are vested in the Company retirement contribution upon completion of 2 years of service. In addition, a participant’s entire account balance becomes 100% vested and payable upon the participant’s attainment of age 65, disability, or death.

Distribution of Benefits

The benefit to which a participant is entitled is the benefit that can be provided from the participant’s vested account. Benefits may be distributed to participants upon termination of employment by reason of retirement, disability, death or other severance of employment. Participants who terminate employment and have a vested account balance of less than $1,000 will receive a lump sum distribution of 100% of their vested benefits. Distributions for participants with vested account balances greater than $1,000 but not in excess of $5,000 who terminate employment and fail to make a distribution election will be paid to an individual retirement account designated by the plan administrator. Participants who have attained age 55 may elect to receive benefit payments in cash installments or a lump sum distribution. Participants who have not attained age 55 must receive benefit payments in a lump sum distribution.

A participant may withdraw up to 100% of his or her

before-tax

or Roth contributions upon showing a financial hardship exists, as defined by the Plan, but only after the participant has withdrawn all other vested benefits from the Plan and the maximum loan has been made from the participant’s account. Participants may withdraw at any time any

after-tax

contributions made. A participant may make withdrawals from his or her entire vested account balance once the participant reaches age 59

A participant may elect to defer payment of a benefit until April 1 following the year that the participant reaches age 73.

Participant Loans

Cabot employees may obtain loans from the Plan in an amount not to exceed, in the aggregate, the lesser of $50,000 or 50% of the total vested amount in the participant’s account. Each loan must be paid in full within

five

years through payroll deductions and is secured by the participant’s remaining account balance. The Plan provides that loans may bear interest at reasonable rates as determined by Cabot Human Resources. The interest rate is currently the

prime rate plus 2%,

and is adjusted quarterly for new loans to reflect changes in the prime rate. Interest rates on outstanding loans as of December 31, 2025 ranged from 5.25% to 10.50% per annum. Participant loans are classified as notes receivable from participants on the Statements of Net Assets Available for Benefits.

Fair Value Measurements

12 Months Ended

Dec. 31, 2025

EBP 022 [Member]

EBP, Investment, Fair Value and NAV [Line Items]

Fair Value Measurements

3.	Fair Value Measurements

The Plan classifies its investments into Level 1, which refers to securities valued using quoted prices from active markets for identical assets; Level 2, which refers to securities not traded on an active market but for which observable market inputs are readily available; and Level 3, which refers to securities valued based on significant unobservable inputs. Assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. There were no transfers of assets between levels during the year ended December 31, 2025. The Plan’s policy is to recognize significant transfers between levels at the beginning of the reporting period.

Following is a description of the valuation methodologies used by the Plan. There have been no changes in the methodologies used between December 31, 2025 and 2024.

Common collective trust

– The Vanguard Retirement Savings Trust (“VRST”), a common collective trust, invests primarily in synthetic guaranteed investment contracts and short-term money market funds. The VRST is valued at the net asset value (“NAV”) as provided by the trustee, which is used as a practical expedient to estimate fair value. The NAV is based on the fair value of the underlying investments held by the fund less its liabilities and then divided by number of shares outstanding. This practical expedient is not used when it is determined to be probable that the fund will sell the investment for an amount different than the reported NAV. The Plan has no unfunded commitments to the VRST, which allows for daily transactions. The Plan may be subject to a

12-month

notice period for redemptions. Redemptions are allowed daily for participants. The VRST is audited annually. MFS Growth Equity CL S is also a common collective trust and invests primarily in US Large Cap equites. Like the VRST, MFS Growth Equity is valued at the net asset value (“NAV”) as provided by the trustee, which is used as a practical expedient to estimate fair value. The NAV is based on the fair value of the underlying investments held by the fund less its liabilities and then divided by number of shares outstanding. The Plan has no unfunded commitments to the MFS Growth Equity, which allows for daily transactions. Unlike the VRST, it is fully liquid and is not subject to a

12-month

notice period for redemptions. Redemptions are allowed daily for participants. The MFS Growth fund is audited annually. The Vanguard Target Retirement Trust II target date series is a series of common collective trusts subject to the risks of their underlying funds. They have a fund of funds structure that seeks to build appropriate asset allocation from preselected stock, bond, and cash portfolios. The Income and Income and Growth

Trusts

have a fixed target investment allocation. Each fund is valued at the net asset value

(“NAV”) as provided by the trustee, which is used as a practical expedient to estimate fair value. The NAV is based on the fair value of the underlying investments held by the fund less its liabilities and then divided by number of shares outstanding. The Plan has no unfunded commitments to the Vanguard Target Retirement Trust II target date series, which allows for daily transactions. The series is fully liquid and is not subject to a

12-month

notice period for redemptions. Redemptions are allowed daily for participants. The trusts are also audited annually.

Mutual funds

– Valued at the daily closing price as reported by the fund. Mutual funds held by the Plan are

open-end

mutual funds that are registered with the Securities and Exchange Commission. These funds are required to publish their daily NAV and to transact at that price. The mutual funds held by the Plan are deemed to be actively traded.

Company stock

– Valued at the closing price reported on the active market on which the individual securities are traded.

The preceding methods described may produce a fair value calculation that may not be indicative of the amount realized upon disposition. Furthermore, although the Plan believes its valuation methods are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different fair value measurement at reporting date.

The following tables set forth by level and major categorization within the fair value hierarchy, the Plan’s assets at fair value as of December 31:


	2025
	Total		Level 1		Level 2		Level 3
Mutual funds	$	552,163,935	$	552,163,935	$	—	$	—
Company stock*		40,128,718		40,128,718		—		—

Total assets in fair value hierarchy		592,292,653		592,292,653		—		—
Common collective trusts**		327,977,770		—		—		—

Total	$	920,270,423	$	592,292,653	$	—	$	—


	2024
	Total		Level 1		Level 2		Level 3
Mutual funds	$	506,445,493	$	506,445,493	$	—	$	—
Company stock*		63,319,850		63,319,850		—		—

Total assets in fair value hierarchy		569,765,343		569,765,343		—		—
Common collective trusts**		302,198,561		—		—		—

Total	$	871,963,904	$	569,765,343	$	—	$	—

*	Includes both Cabot Common ESOP Stock Fund and Cabot Common Stock Fund.

In accordance with Subtopic

820-10,

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

- Definition

The entire disclosure for fair value of investment held by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)), including, but not limited to, fair value measured at net asset value per share as practical expedient (NAV).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 962
-SubTopic 325
-Name Accounting Standards Codification
-Section 45
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477509/962-325-45-5

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-3

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-3

Reference 10: http://www.xbrl.org/2003/role/exampleRef
-Topic 962
-SubTopic 325
-Name Accounting Standards Codification
-Section 55
-Paragraph 17
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478873/962-325-55-17

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 962
-SubTopic 325
-Name Accounting Standards Codification
-Section 45
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477509/962-325-45-6

Reference 13: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 23
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482907/825-10-50-23

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 962
-SubTopic 205
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6A-04(3)(b))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477804/962-205-S99-1

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 962
-SubTopic 205
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6A-02(a))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477804/962-205-S99-1

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 962
-SubTopic 205
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6A-04(2)(b))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477804/962-205-S99-1

+ Details

Statement of Changes in Net Assets Available for Benefits - EBP 022 [Member]	12 Months Ended
	Dec. 31, 2025 USD ($)
Additions
Interest and dividend income	$ 27,750,520
Interest on notes receivable from participants	333,280
Net appreciation in fair value of investments	78,375,585
Subtotal of additions	106,459,385
Contributions
Employer contributions	14,195,950
Participant contributions	14,589,405
Rollovers	1,790,287
Subtotal of contributions	30,575,642
Total additions	137,035,027
Deductions
Benefits paid to participants	88,064,122
Administrative expenses	269,123
Subtotal of Deductions	88,333,245
Total Net increase in net assets	48,701,782
Beginning of year	875,636,357
End of year	$ 924,338,139

Schedule H, Line 4i- Schedule of Assets (Held at End of Year) (Detail) - EBP 022 [Member] - USD ($)

12 Months Ended

Dec. 31, 2025

Dec. 31, 2024

EBP, Schedule of Asset Held for Investment [Line Items]

Entity Tax Identification Number

04-2271897

EBP, Plan Number

022

EBP, Note Receivable from Participant

$ 3,617,716

^[1]

$ 3,393,279

EBP, Asset Held for Investment

923,888,139

EBP, Asset Held for Investment, Plan Interest in Master Trust, Current Value

$ 920,270,423

Investment, Identifier [Axis]: Cabot Corporation | Company Stock

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Investment, Issuer Name [Extensible Enumeration]

Cabot Corporation [Member]

EBP, Investment, Current Value, Type [Extensible Enumeration]

Company Stock [Member]

EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration]

EBP, Participant-Directed [Member]

EBP, Asset Held for Investment, Plan Interest in Master Trust, Current Value

^[1]

$ 40,128,718

EBP, Asset Held for Investment, Party-in-Interest [true false]

^[1]

true

Investment, Identifier [Axis]: MFS Growth Equity Fund Class S | Common collective trust

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Investment, Issuer Name [Extensible Enumeration]

MFS Growth Equity Fund Class S [Member]

EBP, Investment, Current Value, Type [Extensible Enumeration]

Common Collective Trust [Member]

EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration]

EBP, Participant-Directed [Member]

EBP, Asset Held for Investment, Plan Interest in Master Trust, Current Value

^[1]

$ 78,774,367

EBP, Asset Held for Investment, Party-in-Interest [true false]

^[1]

true

Investment, Identifier [Axis]: Vanguard Explorer Fund | Mutual fund

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Investment, Issuer Name [Extensible Enumeration]

Vanguard Explorer Fund [Member]

EBP, Investment, Current Value, Type [Extensible Enumeration]

Mutual Fund [Member]

EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration]

EBP, Participant-Directed [Member]

EBP, Asset Held for Investment, Plan Interest in Master Trust, Current Value

^[1]

$ 31,460,073

EBP, Asset Held for Investment, Party-in-Interest [true false]

^[1]

true

Investment, Identifier [Axis]: Vanguard Extended Market Index Fund | Mutual fund

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Investment, Issuer Name [Extensible Enumeration]

Vanguard Extended Market Index Fund [Member]

EBP, Investment, Current Value, Type [Extensible Enumeration]

Mutual Fund [Member]

EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration]

EBP, Participant-Directed [Member]

EBP, Asset Held for Investment, Plan Interest in Master Trust, Current Value

^[1]

$ 42,173,888

EBP, Asset Held for Investment, Party-in-Interest [true false]

^[1]

true

Investment, Identifier [Axis]: Vanguard Federal Money Market Fund | Mutual fund

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Investment, Issuer Name [Extensible Enumeration]

Vanguard Federal Money Market Fund [Member]

EBP, Investment, Current Value, Type [Extensible Enumeration]

Mutual Fund [Member]

EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration]

EBP, Participant-Directed [Member]

EBP, Asset Held for Investment, Plan Interest in Master Trust, Current Value

^[1]

$ 772,359

EBP, Asset Held for Investment, Party-in-Interest [true false]

^[1]

true

Investment, Identifier [Axis]: Vanguard Inflation-Protected Securities Fund: Adm Shares | Mutual fund

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Investment, Issuer Name [Extensible Enumeration]

Vanguard InflationProtected Securities Fund Adm Shares [Member]

EBP, Investment, Current Value, Type [Extensible Enumeration]

Mutual Fund [Member]

EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration]

EBP, Participant-Directed [Member]

EBP, Asset Held for Investment, Plan Interest in Master Trust, Current Value

^[1]

$ 6,474,952

EBP, Asset Held for Investment, Party-in-Interest [true false]

^[1]

true

Investment, Identifier [Axis]: Vanguard Institutional Index Fund | Mutual fund

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Investment, Issuer Name [Extensible Enumeration]

Vanguard Institutional Index Fund [Member]

EBP, Investment, Current Value, Type [Extensible Enumeration]

Mutual Fund [Member]

EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration]

EBP, Participant-Directed [Member]

EBP, Asset Held for Investment, Plan Interest in Master Trust, Current Value

^[1]

$ 187,678,826

EBP, Asset Held for Investment, Party-in-Interest [true false]

^[1]

true

Investment, Identifier [Axis]: Vanguard International Growth Fund | Mutual fund

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Investment, Issuer Name [Extensible Enumeration]

Vanguard International Growth Fund [Member]

EBP, Investment, Current Value, Type [Extensible Enumeration]

Mutual Fund [Member]

EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration]

EBP, Participant-Directed [Member]

EBP, Asset Held for Investment, Plan Interest in Master Trust, Current Value

^[1]

$ 31,787,218

EBP, Asset Held for Investment, Party-in-Interest [true false]

^[1]

true

Investment, Identifier [Axis]: Vanguard International Value Fund | Mutual fund

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Investment, Issuer Name [Extensible Enumeration]

Vanguard International Value Fund [Member]

EBP, Investment, Current Value, Type [Extensible Enumeration]

Mutual Fund [Member]

EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration]

EBP, Participant-Directed [Member]

EBP, Asset Held for Investment, Plan Interest in Master Trust, Current Value

^[1]

$ 9,076,017

EBP, Asset Held for Investment, Party-in-Interest [true false]

^[1]

true

Investment, Identifier [Axis]: Vanguard Retirement Savings Trust III | Common collective trust

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Investment, Issuer Name [Extensible Enumeration]

Vanguard Retirement Savings Trust III [Member]

EBP, Investment, Current Value, Type [Extensible Enumeration]

Common Collective Trust [Member]

EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration]

EBP, Participant-Directed [Member]

EBP, Asset Held for Investment, Plan Interest in Master Trust, Current Value

^[1]

$ 31,672,951

EBP, Asset Held for Investment, Party-in-Interest [true false]

^[1]

true

Investment, Identifier [Axis]: Vanguard Short-term Federal Fund | Mutual fund

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Investment, Issuer Name [Extensible Enumeration]

Vanguard Shortterm Federal Fund [Member]

EBP, Investment, Current Value, Type [Extensible Enumeration]

Mutual Fund [Member]

EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration]

EBP, Participant-Directed [Member]

EBP, Asset Held for Investment, Plan Interest in Master Trust, Current Value

^[1]

$ 17,810,768

EBP, Asset Held for Investment, Party-in-Interest [true false]

^[1]

true

Investment, Identifier [Axis]: Vanguard Target Retirement 2020 Trust II | Common collective trust

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Investment, Issuer Name [Extensible Enumeration]

Vanguard Target Retirement 2020 Trust II [Member]

EBP, Investment, Current Value, Type [Extensible Enumeration]

Common Collective Trust [Member]

EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration]

EBP, Participant-Directed [Member]

EBP, Asset Held for Investment, Plan Interest in Master Trust, Current Value

^[1]

$ 10,526,514

EBP, Asset Held for Investment, Party-in-Interest [true false]

^[1]

true

Investment, Identifier [Axis]: Vanguard Target Retirement 2025 Trust II | Common collective trust

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Investment, Issuer Name [Extensible Enumeration]

Vanguard Target Retirement 2025 Trust II [Member]

EBP, Investment, Current Value, Type [Extensible Enumeration]

Common Collective Trust [Member]

EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration]

EBP, Participant-Directed [Member]

EBP, Asset Held for Investment, Plan Interest in Master Trust, Current Value

^[1]

$ 12,754,099

EBP, Asset Held for Investment, Party-in-Interest [true false]

^[1]

true

Investment, Identifier [Axis]: Vanguard Target Retirement 2030 Trust II | Common collective trust

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Investment, Issuer Name [Extensible Enumeration]

Vanguard Target Retirement 2030 Trust II [Member]

EBP, Investment, Current Value, Type [Extensible Enumeration]

Common Collective Trust [Member]

EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration]

EBP, Participant-Directed [Member]

EBP, Asset Held for Investment, Plan Interest in Master Trust, Current Value

^[1]

$ 38,858,350

EBP, Asset Held for Investment, Party-in-Interest [true false]

^[1]

true

Investment, Identifier [Axis]: Vanguard Target Retirement 2035 Trust II | Common collective trust

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Investment, Issuer Name [Extensible Enumeration]

Vanguard Target Retirement 2035 Trust II [Member]

EBP, Investment, Current Value, Type [Extensible Enumeration]

Common Collective Trust [Member]

EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration]

EBP, Participant-Directed [Member]

EBP, Asset Held for Investment, Plan Interest in Master Trust, Current Value

^[1]

$ 31,540,660

EBP, Asset Held for Investment, Party-in-Interest [true false]

^[1]

true

Investment, Identifier [Axis]: Vanguard Target Retirement 2040 Trust II | Common collective trust

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Investment, Issuer Name [Extensible Enumeration]

Vanguard Target Retirement 2040 Trust II [Member]

EBP, Investment, Current Value, Type [Extensible Enumeration]

Common Collective Trust [Member]

EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration]

EBP, Participant-Directed [Member]

EBP, Asset Held for Investment, Plan Interest in Master Trust, Current Value

^[1]

$ 25,569,787

EBP, Asset Held for Investment, Party-in-Interest [true false]

^[1]

true

Investment, Identifier [Axis]: Vanguard Target Retirement 2045 Trust II | Common collective trust

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Investment, Issuer Name [Extensible Enumeration]

Vanguard Target Retirement 2045 Trust II [Member]

EBP, Investment, Current Value, Type [Extensible Enumeration]

Common Collective Trust [Member]

EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration]

EBP, Participant-Directed [Member]

EBP, Asset Held for Investment, Plan Interest in Master Trust, Current Value

^[1]

$ 30,041,639

EBP, Asset Held for Investment, Party-in-Interest [true false]

^[1]

true

Investment, Identifier [Axis]: Vanguard Target Retirement 2050 Trust II | Common collective trust

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Investment, Issuer Name [Extensible Enumeration]

Vanguard Target Retirement 2050 Trust II [Member]

EBP, Investment, Current Value, Type [Extensible Enumeration]

Common Collective Trust [Member]

EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration]

EBP, Participant-Directed [Member]

EBP, Asset Held for Investment, Plan Interest in Master Trust, Current Value

^[1]

$ 31,012,717

EBP, Asset Held for Investment, Party-in-Interest [true false]

^[1]

true

Investment, Identifier [Axis]: Vanguard Target Retirement 2055 Trust II | Common collective trust

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Investment, Issuer Name [Extensible Enumeration]

Vanguard Target Retirement 2055 Trust II [Member]

EBP, Investment, Current Value, Type [Extensible Enumeration]

Common Collective Trust [Member]

EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration]

EBP, Participant-Directed [Member]

EBP, Asset Held for Investment, Plan Interest in Master Trust, Current Value

^[1]

$ 17,130,703

EBP, Asset Held for Investment, Party-in-Interest [true false]

^[1]

true

Investment, Identifier [Axis]: Vanguard Target Retirement 2060 Trust II | Common collective trust

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Investment, Issuer Name [Extensible Enumeration]

Vanguard Target Retirement 2060 Trust II [Member]

EBP, Investment, Current Value, Type [Extensible Enumeration]

Common Collective Trust [Member]

EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration]

EBP, Participant-Directed [Member]

EBP, Asset Held for Investment, Plan Interest in Master Trust, Current Value

^[1]

$ 7,784,829

EBP, Asset Held for Investment, Party-in-Interest [true false]

^[1]

true

Investment, Identifier [Axis]: Vanguard Target Retirement 2065 Trust II | Common collective trust

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Investment, Issuer Name [Extensible Enumeration]

Vanguard Target Retirement 2065 Trust II [Member]

EBP, Investment, Current Value, Type [Extensible Enumeration]

Common Collective Trust [Member]

EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration]

EBP, Participant-Directed [Member]

EBP, Asset Held for Investment, Plan Interest in Master Trust, Current Value

^[1]

$ 3,063,372

EBP, Asset Held for Investment, Party-in-Interest [true false]

^[1]

true

Investment, Identifier [Axis]: Vanguard Target Retirement 2070 Trust II| Common collective trust

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Investment, Issuer Name [Extensible Enumeration]

Vanguard Target Retirement 2070 Trust II [Member]

EBP, Investment, Current Value, Type [Extensible Enumeration]

Common Collective Trust [Member]

EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration]

EBP, Participant-Directed [Member]

EBP, Asset Held for Investment, Plan Interest in Master Trust, Current Value

^[1]

$ 546,925

EBP, Asset Held for Investment, Party-in-Interest [true false]

^[1]

true

Investment, Identifier [Axis]: Vanguard Target Retirement Income Trust II | Common collective trust

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Investment, Issuer Name [Extensible Enumeration]

Vanguard Target Retirement Income Trust II [Member]

EBP, Investment, Current Value, Type [Extensible Enumeration]

Common Collective Trust [Member]

EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration]

EBP, Participant-Directed [Member]

EBP, Asset Held for Investment, Plan Interest in Master Trust, Current Value

^[1]

$ 8,693,862

EBP, Asset Held for Investment, Party-in-Interest [true false]

^[1]

true

Investment, Identifier [Axis]: Vanguard Target Retirement Income and Growth Trust II | Common collective trust

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Investment, Issuer Name [Extensible Enumeration]

Vanguard Target Retirement Income and Growth Trust II [Member]

EBP, Investment, Current Value, Type [Extensible Enumeration]

Common Collective Trust [Member]

EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration]

EBP, Participant-Directed [Member]

EBP, Asset Held for Investment, Plan Interest in Master Trust, Current Value

^[1]

$ 6,995

EBP, Asset Held for Investment, Party-in-Interest [true false]

^[1]

true

Investment, Identifier [Axis]: Vanguard Total Bond Market Index Fund | Mutual fund

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Investment, Issuer Name [Extensible Enumeration]

Vanguard Total Bond Market Index Fund [Member]

EBP, Investment, Current Value, Type [Extensible Enumeration]

Mutual Fund [Member]

EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration]

EBP, Participant-Directed [Member]

EBP, Asset Held for Investment, Plan Interest in Master Trust, Current Value

^[1]

$ 64,937,034

EBP, Asset Held for Investment, Party-in-Interest [true false]

^[1]

true

Investment, Identifier [Axis]: Vanguard Total International Bond Index Fund | Mutual fund

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Investment, Issuer Name [Extensible Enumeration]

Vanguard Total International Bond Index Fund [Member]

EBP, Investment, Current Value, Type [Extensible Enumeration]

Mutual Fund [Member]

EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration]

EBP, Participant-Directed [Member]

EBP, Asset Held for Investment, Plan Interest in Master Trust, Current Value

^[1]

$ 13,407,219

EBP, Asset Held for Investment, Party-in-Interest [true false]

^[1]

true

Investment, Identifier [Axis]: Vanguard Total International Stock Index Fund | Mutual fund

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Investment, Issuer Name [Extensible Enumeration]

Vanguard Total International Stock Index Fund [Member]

EBP, Investment, Current Value, Type [Extensible Enumeration]

Mutual Fund [Member]

EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration]

EBP, Participant-Directed [Member]

EBP, Asset Held for Investment, Plan Interest in Master Trust, Current Value

^[1]

$ 51,497,298

EBP, Asset Held for Investment, Party-in-Interest [true false]

^[1]

true

Investment, Identifier [Axis]: Vanguard Wellington Fund | Mutual fund

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Investment, Issuer Name [Extensible Enumeration]

Vanguard Wellington Fund [Member]

EBP, Investment, Current Value, Type [Extensible Enumeration]

Mutual Fund [Member]

EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration]

EBP, Participant-Directed [Member]

EBP, Asset Held for Investment, Plan Interest in Master Trust, Current Value

^[1]

$ 53,527,889

EBP, Asset Held for Investment, Party-in-Interest [true false]

^[1]

true

Investment, Identifier [Axis]: Vanguard Windsor II Fund | Mutual fund

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Investment, Issuer Name [Extensible Enumeration]

Vanguard Windsor II Fund [Member]

EBP, Investment, Current Value, Type [Extensible Enumeration]

Mutual Fund [Member]

EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration]

EBP, Participant-Directed [Member]

EBP, Asset Held for Investment, Plan Interest in Master Trust, Current Value

^[1]

$ 41,560,394

EBP, Asset Held for Investment, Party-in-Interest [true false]

^[1]

true

Maximum [Member]

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Asset Held for Investment, Participant Loan, Interest Rate

10.50%

Maximum [Member] | Investment, Identifier [Axis]: Notes Receivable from Participants

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Asset Held for Investment, Participant Loan, Interest Rate

10.50%

Minimum [Member]

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Asset Held for Investment, Participant Loan, Interest Rate

5.25%

Minimum [Member] | Investment, Identifier [Axis]: Notes Receivable from Participants

EBP, Schedule of Asset Held for Investment [Line Items]

EBP, Asset Held for Investment, Participant Loan, Interest Rate

5.25%

[1]	Indicates party-in-interest to the Plan

Cover	12 Months Ended
Cover	Dec. 31, 2025
Document Information [Line Items]
Document Type	11-K
Amendment Flag	false
Entity Registrant Name	CABOT CORP
Entity Central Index Key	0000016040
EBP 022 [Member]
Document Information [Line Items]
Document Type	11-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2025
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	FY
Entity Registrant Name	CABOT CORP
Entity Central Index Key	0000016040
Current Fiscal Year End Date	--12-31

Federal Income Tax Status - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2025
EBP 022 [Member]
EBP, Tax Status [Line Items]
EBP, tax determination letter, date	Jul. 09, 2014

Forfeitures - Additional Information (Detail) - EBP 022 [Member] - USD ($)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Employee Benefit Plan Forfeited Nonvested Account [Line Items]
Participant forfeitures toward the payment of the Company contribution	$ 300,328
EBP, forfeited nonvested account	$ 91,658	$ 233,406