XML 36 R26.htm IDEA: XBRL DOCUMENT
v3.20.2

MARKETABLE SECURITIES (Tables) | 6 Months Ended
--- | ---
Jun. 30, 2020
MARKETABLE SECURITIES |
Schedule of net realized (losses) gains and reclassification of net realized (losses) gains from other comprehensive income | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Three months ended | ​ | Six months ended
​ | ​ | June 30, | ​ | June 30,
(in thousands) |  | 2020 |  | 2019 |  | 2020 |  | 2019
Net realized gain | ​ | $ | — | ​ | $ | — | ​ | $ | — | ​ | $ | 4
Reclassification of net realized gains from other comprehensive income | ​ | $ | — | ​ | $ | — | ​ | $ | — | ​ | $ | 4

X
- Definition Tabular disclosure of net realized gains and the reclassification of net realized gains from other comprehensive income. + References No definition available. + Details
Name: | mpx_ScheduleOfNetRealizedGainLossAndReclassificationTableTextBlock
Namespace Prefix: | mpx_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

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