Refers to percentage of annual depreciation rate charge for property, plant and equipment.

No definition available.

Name:	mtx_AnnualDepreciationRate
Namespace Prefix:	mtx_
Data Type:	dtr:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Estimate-to-actual adjustment to revenue for shipments sold to customers under PCC contracts. During the year, the price per ton billed to customers is based on periodic estimates of the total annual volume that will be sold to the customer. Revenues are adjusted at the end of each year to reflect the actual volume sold.

+ References

No definition available.

+ Details

Name:	mtx_EstimateToActualRevenueAdjustment
Namespace Prefix:	mtx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The initial length of time long-term evergreen contracts for the sale of Precipitated Calcium Carbonate (PCC) are in effect, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	mtx_InitialTermOfEvergreenContracts
Namespace Prefix:	mtx_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The length of time for which a receivable is past due that will trigger an individual review for collectability, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	mtx_PastDueThresholdForIndividualCollectabilityReview
Namespace Prefix:	mtx_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of allowance for credit loss on accounts receivable, classified as current.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(4))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479344/326-20-45-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-4

+ Details

Name:	us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 270
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482964/270-10-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Name Accounting Standards Codification
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-32

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 323
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-Name Accounting Standards Codification
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Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 323
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-Name Accounting Standards Codification
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-Publisher FASB
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Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(10))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 25
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-25

+ Details

Name:	us-gaap_EquityMethodInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- 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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 7A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-7A

+ Details

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

- Definition

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

+ Details

Name:	us-gaap_PropertyPlantAndEquipmentUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of investments including trading securities, available-for-sale securities, held-to-maturity securities, and short-term investments classified as other and current.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(4))
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-Topic 942
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-Paragraph 1
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Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(8))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

+ Details

Name:	us-gaap_ShortTermInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of unrealized gain (loss) on investment.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 28
-Subparagraph (b)
-SubTopic 10
-Topic 230
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-28

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
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Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_BuildingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_MachineryAndEquipmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_FurnitureAndFixturesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=mtx_ComputerEquipmentAndSoftwareRelatedAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=mtx_MachineryAndEquipmentForNaturalStoneMiningAndProcessingPlantsAndChemicalPlantsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_ManufacturingFacilityMember
Namespace Prefix:
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Summary of Significant Accounting Policies (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2025
Summary of Significant Accounting Policies [Abstract]
Short-term investments	$ 3.6	$ 4.0	$ 3.6
Unrealized holding gains or losses on short-term bank investments			$ 0.0
Past due threshold for individual collectability review			90 days
Allowance for doubtful accounts	16.7	17.1	$ 16.7
Equity method investment	24.7	23.4	$ 24.7
Revenue adjustments	$ 0.0	$ 0.0
Minimum [Member]
Summary of Significant Accounting Policies [Abstract]
Initial term of long-term evergreen contracts			10 years
Maximum [Member]
Summary of Significant Accounting Policies [Abstract]
Initial term of long-term evergreen contracts			15 years
Buildings [Member] \| Minimum [Member]
Summary of Significant Accounting Policies [Abstract]
Annual rates of depreciation			3.00%
Buildings [Member] \| Maximum [Member]
Summary of Significant Accounting Policies [Abstract]
Annual rates of depreciation			6.67%
Machinery and Equipment [Member] \| Minimum [Member]
Summary of Significant Accounting Policies [Abstract]
Annual rates of depreciation			6.67%
Machinery and Equipment [Member] \| Maximum [Member]
Summary of Significant Accounting Policies [Abstract]
Annual rates of depreciation			12.50%
Furniture and Fixtures [Member] \| Minimum [Member]
Summary of Significant Accounting Policies [Abstract]
Annual rates of depreciation			8.00%
Furniture and Fixtures [Member] \| Maximum [Member]
Summary of Significant Accounting Policies [Abstract]
Annual rates of depreciation			12.50%
Computer Equipment and Software-related Assets [Member] \| Minimum [Member]
Summary of Significant Accounting Policies [Abstract]
Annual rates of depreciation			12.50%
Computer Equipment and Software-related Assets [Member] \| Maximum [Member]
Summary of Significant Accounting Policies [Abstract]
Annual rates of depreciation			25.00%
Machinery and Equipment for Natural Stone Mining and Processing Plants and Chemical Plants [Member]
Summary of Significant Accounting Policies [Abstract]
Estimated useful life	15 years		15 years
PCC Production Facilities [Member]
Summary of Significant Accounting Policies [Abstract]
Estimated useful life	15 years		15 years