Financial instruments and financial risk factors - Additional Information (Detail)	12 Months Ended
Oct. 31, 2020	Jul. 31, 2021
Disclosure of fair value measurement of liabilities [line items]
Description about transfers between levels	There were no transfers between the levels during the current or prior year.
Interest rate risk [member]
Disclosure of fair value measurement of liabilities [line items]
Debt instrument, interest rate	0.00%	0.00%

The statement that there were no transfers between Level 1, Level 2 or Level 3 of the fair value hierarchy of liabilities during the year.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IFRS
-Number 13
-IssueDate 2020-01-01
-Paragraph 93
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=13&code=ifrs-tx-2020-en-r&anchor=para_93_c&doctype=Standard
-URIDate 2020-01-01

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IFRS
-Number 13
-IssueDate 2020-01-01
-Paragraph 93
-Subparagraph e
-Clause iv
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=13&code=ifrs-tx-2020-en-r&anchor=para_93_e_iv&doctype=Standard
-URIDate 2020-01-01

Name:	ifrs-full_StatementThatThereWereNoTransfersBetweenLevel1Level2OrLevel3OfFairValueHierarchyLiabilities
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration