XML 81 R63.htm IDEA: XBRL DOCUMENT
v3.24.0.1

Fair Value of Financial Instruments (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2023 | Dec. 31, 2022
Additional Fair Value Elements [Abstract] |  |
Transfers in or out of Level 3 | $ 0.0 | $ 0.0
Fair Value, Measurements, Recurring [Member] |  |
Additional Fair Value Elements [Abstract] |  |
Deferred compensation plan assets | 13.7 | 13.6
Supplementary pension plan assets | 15.5 | 13.5
Cross currency rate swap |  | 13.8
Interest rate swap | (0.1) | 1.0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] |  |
Additional Fair Value Elements [Abstract] |  |
Deferred compensation plan assets | 0.0 | 0.0
Supplementary pension plan assets | 0.0 | 0.0
Cross currency rate swap |  | 0.0
Interest rate swap | 0.0 | 0.0
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |
Additional Fair Value Elements [Abstract] |  |
Deferred compensation plan assets | 13.7 | 13.6
Supplementary pension plan assets | 15.5 | 13.5
Cross currency rate swap |  | 13.8
Interest rate swap | (0.1) | 1.0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |
Additional Fair Value Elements [Abstract] |  |
Deferred compensation plan assets | 0.0 | 0.0
Supplementary pension plan assets | 0.0 | 0.0
Cross currency rate swap |  | 0.0
Interest rate swap | $ 0.0 | $ 0.0

X
- Definition Fair value portion of asset contracts related to deferred compensation plan. + References No definition available. + Details
Name: | mtx_DeferredCompensationPlanAssetFairValueDisclosure
Namespace Prefix: | mtx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value portion of asset contracts related to interest rate swaps. + References No definition available. + Details
Name: | mtx_InterestRateSwapAssetsFairValueDisclosure
Namespace Prefix: | mtx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value portion of asset contracts related to supplementary pension plan. + References No definition available. + Details
Name: | mtx_SupplementaryPensionPlanAssetFairValueDisclosure
Namespace Prefix: | mtx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_AdditionalFairValueElementsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of transfers of financial instrument classified as a liability into (out of) level 3 of the fair value hierarchy. + References No definition available. + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityTransfersNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Fair value portion of asset contracts related to the exchange of different currencies, including, but not limited to, foreign currency options, forward contracts, and swaps. + References No definition available. + Details
Name: | us-gaap_ForeignCurrencyContractAssetFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |