Discontinued Operations (Details) - Jun. 29, 2014 - USD ($) $ in Millions	Total	Total
Discontinued Operations [Abstract]
Reversal of facility closure accrual costs, net of tax	$ 1.8	$ 1.8
Tax expense (benefit) on facility closure accrual costs	$ 0.6	$ 0.6

Amount of tax expense (benefit) of reversal of facility closure costs attributable to disposal group.

No definition available.

Name:	mtx_DisposalGroupIncludingDiscontinuedOperationReversalOfFacilityClosureAccrualCostsTaxExpenseBenefit
Namespace Prefix:	mtx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration