Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
Dec. 31, 2021
Disclosure Of Significant Accounting Policies [Line Items]
Percentage of bid amount to be included in inventory	51.00%
De Beers [Member]
Disclosure Of Significant Accounting Policies [Line Items]
Percentage of bid price as revenue	49.00%

The element represents the percentage of bid amount to be included in inventory.

No definition available.

Name:	mpvd_PercentageOfBidAmountToBeIncludedInIventory
Namespace Prefix:	mpvd_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration