LEASE - Disclosure of detailed information about lease liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
Aug. 31, 2023	Aug. 31, 2022	Aug. 31, 2021
Lease liabilities [abstract]
Balance, beginning of year	$ 125	$ 203
Additions	312	0
Accretion of interest	20	14
Payments	(88)	(87)	$ (91)
Foreign Exchange	(3)	(5)
Balance, End of year	365	125	$ 203
Current (included in Accounts Payable)	48	81
Non-current	$ 317	$ 44

The amount of additions to right-of-use assets. [Refer: Right-of-use assets]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 16
-IssueDate 2023-01-01
-Paragraph 53
-Subparagraph h
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=16&code=ifrs-tx-2023-en-r&anchor=para_53_h&doctype=Standard
-URIDate 2023-03-23

+ Details

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

- Definition

The amount of current lease liabilities. [Refer: Lease liabilities]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 16
-IssueDate 2023-01-01
-Paragraph 47
-Subparagraph b
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=16&code=ifrs-tx-2023-en-r&anchor=para_47_b&doctype=Standard
-URIDate 2023-03-23

+ Details

Name:	ifrs-full_CurrentLeaseLiabilities
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of liabilities related to the entity's leases. Lease is a contract, or part of a contract, that conveys the right to use an underlying asset for a period of time in exchange for consideration.

+ References

+ Details

Name:	ifrs-full_LeaseLiabilities
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

Name:	ifrs-full_LeaseLiabilitiesAbstract
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of non-current lease liabilities. [Refer: Lease liabilities]

+ References

+ Details

Name:	ifrs-full_NoncurrentLeaseLiabilities
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The cash outflow for payment of lease liabilities, classified as financing activities. [Refer: Lease liabilities]

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 7
-IssueDate 2023-01-01
-Paragraph 17
-Subparagraph e
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=7&code=ifrs-tx-2023-en-r&anchor=para_17_e&doctype=Standard
-URIDate 2023-03-23

+ Details

Name:	ifrs-full_PaymentsOfLeaseLiabilitiesClassifiedAsFinancingActivities
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Accretion of interest on lease liabilities.

+ References

No definition available.

+ Details

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

- Definition

The increase (decrease) in lease liabilities resulting from foreign exchange.

+ References

No definition available.

+ Details

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