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Segment and Related Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 28, 2014	Jun. 29, 2014	Mar. 30, 2014	Dec. 31, 2013	Sep. 29, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014 Segment	Dec. 31, 2013 Segment	Dec. 31, 2012
Segment and Related Information [Abstract]
Number of Reportable Segments									5us-gaap_NumberOfReportableSegments	2us-gaap_NumberOfReportableSegments
Segment Reporting Information [Line Items]
Net sales	$ 516.0us-gaap_SalesRevenueNet	$ 543.5us-gaap_SalesRevenueNet	$ 421.1us-gaap_SalesRevenueNet	$ 244.4us-gaap_SalesRevenueNet	$ 256.8us-gaap_SalesRevenueNet	$ 254.2us-gaap_SalesRevenueNet	$ 256.8us-gaap_SalesRevenueNet	$ 250.4us-gaap_SalesRevenueNet	$ 1,725.0us-gaap_SalesRevenueNet	$ 1,018.2us-gaap_SalesRevenueNet	$ 996.8us-gaap_SalesRevenueNet
Income from operations	42.6us-gaap_OperatingIncomeLoss	66.8us-gaap_OperatingIncomeLoss	35.8us-gaap_OperatingIncomeLoss	23.6us-gaap_OperatingIncomeLoss	33.5us-gaap_OperatingIncomeLoss	32.8us-gaap_OperatingIncomeLoss	32.4us-gaap_OperatingIncomeLoss	28.2us-gaap_OperatingIncomeLoss	168.8us-gaap_OperatingIncomeLoss	126.9us-gaap_OperatingIncomeLoss	113.6us-gaap_OperatingIncomeLoss
Restructuring and other charges									43.2us-gaap_RestructuringCharges	0us-gaap_RestructuringCharges	0us-gaap_RestructuringCharges
Depreciation, depletion and amortization									84.4	47.3	51.1
Segment assets	3,226.7us-gaap_Assets				1,217.5us-gaap_Assets				3,226.7us-gaap_Assets	1,217.5us-gaap_Assets	1,211.2us-gaap_Assets
Capital expenditures									81.8	43.8	52.1
Goodwill	770.9us-gaap_Goodwill				64.4us-gaap_Goodwill				770.9us-gaap_Goodwill	64.4us-gaap_Goodwill	65.8us-gaap_Goodwill
Income from operations before provision for taxes on income [Abstract]
Income from operations	42.6us-gaap_OperatingIncomeLoss	66.8us-gaap_OperatingIncomeLoss	35.8us-gaap_OperatingIncomeLoss	23.6us-gaap_OperatingIncomeLoss	33.5us-gaap_OperatingIncomeLoss	32.8us-gaap_OperatingIncomeLoss	32.4us-gaap_OperatingIncomeLoss	28.2us-gaap_OperatingIncomeLoss	168.8us-gaap_OperatingIncomeLoss	126.9us-gaap_OperatingIncomeLoss	113.6us-gaap_OperatingIncomeLoss
Acquisition related transaction and integration costs									(19.1)	0	0
Unallocated corporate expenses									(7.6)mtx_UnallocatedCorporateExpenses	(7.4)mtx_UnallocatedCorporateExpenses	(6.7)mtx_UnallocatedCorporateExpenses
Non-operating deductions, net									(45.8)us-gaap_NonoperatingIncomeExpense	(3.2)us-gaap_NonoperatingIncomeExpense	(3.0)us-gaap_NonoperatingIncomeExpense
Income from continuing operations before provision for taxes on income									123.0	123.7	110.6
Specialty Minerals [Member]
Segment Reporting Information [Line Items]
Net sales	159.6	163.0	167.8	159.7	167.3	167.4	168.3	166.8
Goodwill	13.7				14.3				13.7	14.3	14.1
Refractories [Member]
Segment Reporting Information [Line Items]
Net sales	92.9	90.4	91.7	84.7	89.5	86.8	88.5	83.6
Goodwill	49.0				50.1				49.0	50.1	51.7
Performance Materials [Member]
Segment Reporting Information [Line Items]
Net sales	141.4	135.6	75.8	0
Goodwill	453.2				0				453.2	0	0
Construction Technologies [Member]
Segment Reporting Information [Line Items]
Net sales	46.0	69.1	37.2	0
Goodwill	255.0				0				255.0	0	0
Energy Services [Member]
Segment Reporting Information [Line Items]
Net sales	76.1	85.4	48.6	0
Reportable Segments [Member]
Segment Reporting Information [Line Items]
Net sales									1,725.0	1,018.2	996.8
Income from operations									195.5	134.3	120.3
Depreciation, depletion and amortization									84.4	47.3	51.1
Segment assets	3,112.7				983.7				3,112.7	983.7	972.5
Capital expenditures									81.1	41.9	49.0
Income from operations before provision for taxes on income [Abstract]
Income from operations									195.5	134.3	120.3
Reportable Segments [Member] \| Specialty Minerals [Member]
Segment Reporting Information [Line Items]
Net sales									650.1	669.8	653.4
Income from operations									95.8	98.4	87.7
Depreciation, depletion and amortization									35.6	38.6	40.8
Segment assets	494.4				605.6				494.4	605.6	617.0
Capital expenditures									44.4	33.6	41.0
Income from operations before provision for taxes on income [Abstract]
Income from operations									95.8	98.4	87.7
Reportable Segments [Member] \| Refractories [Member]
Segment Reporting Information [Line Items]
Net sales									359.7	348.4	343.4
Income from operations									43.2	35.9	32.6
Depreciation, depletion and amortization									10.8	8.7	10.3
Segment assets	357.3				378.1				357.3	378.1	355.5
Capital expenditures									11.7	8.3	8.0
Income from operations before provision for taxes on income [Abstract]
Income from operations									43.2	35.9	32.6
Reportable Segments [Member] \| Performance Materials [Member]
Segment Reporting Information [Line Items]
Net sales									352.8
Income from operations									41.0
Depreciation, depletion and amortization									18.7
Segment assets	1,584.4								1,584.4
Capital expenditures									7.3
Income from operations before provision for taxes on income [Abstract]
Income from operations									41.0
Reportable Segments [Member] \| Construction Technologies [Member]
Segment Reporting Information [Line Items]
Net sales									152.3
Income from operations									(0.8)
Depreciation, depletion and amortization									5.8
Segment assets	447.7								447.7
Capital expenditures									1.0
Income from operations before provision for taxes on income [Abstract]
Income from operations									(0.8)
Reportable Segments [Member] \| Energy Services [Member]
Segment Reporting Information [Line Items]
Net sales									210.1
Income from operations									16.3
Depreciation, depletion and amortization									13.5
Segment assets	228.9								228.9
Capital expenditures									16.7
Income from operations before provision for taxes on income [Abstract]
Income from operations									16.3
Corporate [Member]
Segment Reporting Information [Line Items]
Segment assets	114.0				233.8				114.0	233.8	238.7
Capital expenditures									$ 0.7	$ 1.9	$ 3.1