Contingencies (Details) $ in Millions	3 Months Ended	6 Months Ended
Jun. 29, 2025 USD ($) Claim	Mar. 30, 2025 USD ($) Claim	Jun. 30, 2024 USD ($) Claim	Jun. 29, 2025 USD ($) Claim	Jun. 30, 2024 USD ($) Claim
Contingencies [Abstract]
Provision for DIP Agreement \| $	$ 30.0		$ 30.0
Provision for litigation reserve and credit losses \| $	$ 0.0	$ 215.0	$ 30.0	$ 215.0	$ 30.0
Talc-Related Claims [Member]
Contingencies [Abstract]
Claims pending, beginning of period	715	684	594	684	574
Claims filed	68		49	135	79
Less: Claims dismissed, settled or otherwise resolved	8		5	44	15
Claims pending, end of period	775	715	638	775	638

Amount of expense for claims expected to be incurred by an entity in reorganization.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 852
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 9
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481435/852-10-45-9

+ Details

Name:	us-gaap_DebtorReorganizationItemsProvisionForExpectedAllowedClaims
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount charged against operating income increasing loss contingency liability, after adjustments to reduce previously estimated charges.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 450
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483076/450-20-50-1

+ Details

Name:	us-gaap_LossContingencyAccrualProvision
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The number of claims settled and dismissed during the period.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 450
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483076/450-20-50-4

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 450
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483076/450-20-50-9

+ Details

Name:	us-gaap_LossContingencyClaimsSettledAndDismissedNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

+ Details

Name:	us-gaap_LossContingencyInformationAboutLitigationMattersAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The total number of new claims filed pertaining to a loss contingency during the period.

+ References

+ Details

Name:	us-gaap_LossContingencyNewClaimsFiledNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of pending claims pertaining to a loss contingency.

+ References

+ Details

Name:	us-gaap_LossContingencyPendingClaimsNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=mtx_TalcRelatedClaimsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: