The amount of interest expense on borrowings. [Refer: Interest expense; Borrowings]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2019-01-01
-Paragraph 112
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_112_c&doctype=Standard
-URIDate 2019-03-27

+ Details

Name:	ifrs-full_InterestExpenseOnBorrowings
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Reprsents amount of advanced principal senior secured credit facility.

+ References

No definition available.

+ Details

Name:	ptm_AdvancedAmountOfPrincipalSeniorSecuredCreditFacility
Namespace Prefix:	ptm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents information related to advance loan secured credit facility.

+ References

No definition available.

+ Details

Name:	ptm_DescriptionOfLoanSecuredCreditFacility
Namespace Prefix:	ptm_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

+ References

No definition available.

+ Details

Name:	ptm_DisclosureOfSprottLoanLineItems
Namespace Prefix:	ptm_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Shares issued for loan facilities

+ References

No definition available.

+ Details

Name:	ptm_IncreaseDecreaseThroughSharesIssuedForLoanFacilities
Namespace Prefix:	ptm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Shares issued for loan facilities (Shares)

+ References

No definition available.

+ Details

Name:	ptm_IncreaseDecreaseThroughSharesIssuedForLoanFacilitiesShares
Namespace Prefix:	ptm_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents percentage of loan facility, interest rate.

+ References

No definition available.

+ Details

Name:	ptm_LoanFacilityInterestRate
Namespace Prefix:	ptm_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents amount of payment for monthly interest charge.

+ References

No definition available.

+ Details

Name:	ptm_PaymentForMonthlyInterestCharge
Namespace Prefix:	ptm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	ifrs-full_BorrowingsByNameAxis=ptm_SprottFacilityLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

SPROTT LOAN (Narrative) (Details) - USD ($) $ in Thousands		3 Months Ended	9 Months Ended
SPROTT LOAN (Narrative) (Details) - USD ($) $ in Thousands	Aug. 15, 2019	Aug. 31, 2019	May 31, 2020	May 31, 2019
Disclosure Of Sprott Loan [Line Items]
Shares issued for loan facility		$ 1,000
Shares issued for loan facility (Shares)		800,000
Sprott Facility [Member]
Disclosure Of Sprott Loan [Line Items]
Advanced amount of principal senior secured credit facility	$ 20,000
Description of loan secured credit facility	The loan was drawn August 21, 2019 and is due August 14, 2021 with the Company holding the option to extend the maturity date by one year in exchange for a payment in common shares or cash of three percent of the outstanding principal amount.
Loan facility interest rate	11%
Payment for monthly interest charge			$ 1,674
Interest expense on borrowings			$ 2,096