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v3.19.3.a.u2

Net Sales - Payment Terms (Details) | 12 Months Ended
--- | ---
Dec. 31, 2019
Minimum |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Revenue satisfaction period | 7 days
Maximum |
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] |
Revenue satisfaction period | 10 days

X
- Definition The satisfaction period of revenue remaining performance obligation. + References No definition available. + Details
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Namespace Prefix: | mpx_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

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

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |