Subsequent Event (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
Jul. 04, 2011
Subsequent Event [Line Items]
Non-cash foreign currency translation loss relating to deconsolidation	$ 1.4
Partial Divestiture of Korean Refractories Joint Venture [Member]
Subsequent Event [Line Items]
Date of subsequent event	Jul. 04, 2011
Ownership Interest Divested (in hundredths)	50.00%
Proceeds from divestiture of ownership interest in joint venture	$ 1.5
Ownership interest retained (in hundredths)	20.00%

In connection with deconsolidation of an entity, this element represents the portion of the gain or loss recognized by the parent, during the period, which is related to the recognition of cumulative foreign currency translation gains or losses

Name:	mtx_Deconsolidationtranslationgainorlossamount
Namespace Prefix:	mtx
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The portion of the parent entity's interest in net assets of the subsidiary that was sold or otherwise divested, expressed as a percentage.

+ Details

Name:	mtx_OwnershipInterestDivested
Namespace Prefix:	mtx
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 159
-Paragraph 18
-Subparagraph f
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Principles Board Opinion (APB)
-Number 18
-Paragraph 20
-Subparagraph a (1)
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571

+ Details

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Namespace Prefix:	us-gaap
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Reflects the known or estimated financial effect of the event, or transaction that occurred between the balance sheet date and the date the financial statements are issued or available to be issued.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Topic 855
-SubTopic 10
-Section 50
-Paragraph 2
-Name Accounting Standards Codification
-URI http://asc.fasb.org/extlink&oid=6842918&loc=SL6314017-165662

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 165
-Paragraph 13
-Subparagraph b
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Name:	us-gaap_SubsequentEventAmount
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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.

+ Details

Name:	us-gaap_SubsequentEventLineItems
Namespace Prefix:	us-gaap
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Date of subsequent event occurrence or of indication that subsequent event occurred.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 855
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6842918&loc=SL6314017-165662

+ Details

Name:	us-gaap_SubsequentEventsDate
Namespace Prefix:	us-gaap
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration