Name:	mpx_ChangeInFairValueOfLiabilityUnrealizedGains
Namespace Prefix:	mpx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

This element represents the amount of trading gains (losses) of plan assets under the defined benefit plan.

No definition available.

Name:	mpx_DefinedBenefitPlanTradingGainsLosses
Namespace Prefix:	mpx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

N/A

No definition available.

Name:	mpx_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesDeferralsNetOfDistributionStatedAtFairValue
Namespace Prefix:	mpx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Weighted average rate of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost of defined benefit plan.

Name:	us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

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.

No definition available.

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

Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
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-Section 50
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-Name Accounting Standards Codification
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Name:	us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount of gain (loss) recognized in net periodic benefit (cost) credit from irrevocable action relieving primary responsibility for benefit obligation and eliminating risk related to obligation and assets used to effect settlement.