Inventories - Detailed Information about Inventories (Detail) - CAD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Disclosure Of Inventories Explanatory [Abstract]
Ore stockpile	$ 8,592	$ 17,714
Rough diamonds	70,190	56,300
Supplies inventory	32,990	28,247
Total	$ 111,772	$ 102,261

A classification of current inventory representing the amount of ore stockpiles. [Refer: Inventories]

Name:	ifrs-full_CurrentOreStockpiles
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of current inventories. [Refer: Inventories]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 2
-IssueDate 2019-01-01
-Paragraph 36
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=2&code=ifrs-tx-2019-en-r&anchor=para_36_b&doctype=Standard
-URIDate 2019-03-27

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2019-01-01
-Paragraph 54
-Subparagraph g
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_54_g&doctype=Standard
-URIDate 2019-03-27

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 1
-IssueDate 2019-01-01
-Paragraph 68
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_68&doctype=Standard
-URIDate 2019-03-27

+ Details

Name:	ifrs-full_Inventories
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

A classification of current inventory representing the amount of supplies to be used for the production process. [Refer: Inventories]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 2
-IssueDate 2019-01-01
-Paragraph 37
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=2&code=ifrs-tx-2019-en-r&anchor=para_37&doctype=Standard
-URIDate 2019-03-27

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 1
-IssueDate 2019-01-01
-Paragraph 78
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_78_c&doctype=Standard
-URIDate 2019-03-27

+ Details

Name:	ifrs-full_ProductionSupplies
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

A classification of current inventory representing the amount of rough diamonds.

+ References

No definition available.

+ Details

Name:	mpvd_CurrentRoughDiamonds
Namespace Prefix:	mpvd_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	mpvd_DisclosureOfInventoriesExplanatoryAbstract
Namespace Prefix:	mpvd_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration