BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES - Disclosure of detailed information about foreign exchange rates used (Details)	9 Months Ended
May 31, 2022 CAD_USD Rand_USD	May 31, 2021 CAD_USD Rand_USD	Aug. 31, 2021 CAD_USD Rand_USD
Rand / USD [Member]
Foreign Exchange Rates [Line Items]
Period end rate \| Rand_USD	15.6129		14.5241
Period average rate \| Rand_USD	15.2793	15.215
CAD / USD [Member]
Foreign Exchange Rates [Line Items]
Period end rate \| CAD_USD	1.2648		1.2617
Period average rate \| CAD_USD	1.2661	1.2772

The average exchange rate used by the entity. Exchange rate is the ratio of exchange for two currencies.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2021-01-01
-Paragraph 112
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2021-en-r&anchor=para_112_c&doctype=Standard
-URIDate 2021-03-24

+ Details

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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

- Definition

The spot exchange rate at the end of the reporting period. Exchange rate is the ratio of exchange for two currencies. Spot exchange rate is the exchange rate for immediate delivery.

+ References

+ Details

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Balance Type:	na
Period Type:	instant

- 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

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Period Type:	duration

- Details

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Namespace Prefix:
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Balance Type:
Period Type:

- Details

Name:	srt_CurrencyAxis=ptm_CadUsdMember
Namespace Prefix:
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