Summary of Movement in Derivative Liability (Details) - USD ($)	3 Months Ended	12 Months Ended
Sep. 30, 2020	Sep. 30, 2021
Balance at September 30, 2020
Fair value of derivative liability assumed on Ely acquisition (Note 3)		3,037,702
Change in fair value during the year		1,511,372
Balance at September 30, 2021		$ 4,549,074

Fair value of derivative liability assumed on Ely acquisition.

No definition available.

Name:	GROY_GainsLossesOnChangeInFairValueOfDerivativesOnAcquisition
Namespace Prefix:	GROY_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The gains (losses) resulting from change in the fair value of derivatives recognised in profit or loss. [Refer: Derivatives [member]]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2021-01-01
-Paragraph 85
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2021-en-r&anchor=para_85&doctype=Standard
-URIDate 2021-03-24

+ Details

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

- Definition

The amount of non-current derivative financial liabilities. [Refer: Derivative financial liabilities]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2021-01-01
-Paragraph 55
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2021-en-r&anchor=para_55&doctype=Standard
-URIDate 2021-03-24

+ Details

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