Name:	fsm_FairValueOfNumberOfOtherEquityInstrumentsGrantedInShareBasedPaymentArrangement
Namespace Prefix:	fsm_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

Number of shares authorized for issuance under share-based payment arrangement.

No definition available.

Name:	fsm_IfrsShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized
Namespace Prefix:	fsm_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

No definition available.

Name:	fsm_IfrsShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
Namespace Prefix:	fsm_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

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

No definition available.

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

The amount of expense from share-based payment transactions with employees. [Refer: Expense from share-based payment transactions]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2024-01-01
-Paragraph 112
-Subparagraph c
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2024-en-r&anchor=para_112_c&doctype=Standard
-URIDate 2024-03-27

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

Name:	ifrs-full_TypesOfSharebasedPaymentArrangementsAxis=fsm_DeferredRestrictedAndPerformanceShareUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	ifrs-full_TypesOfSharebasedPaymentArrangementsAxis=ifrs-full_RestrictedShareUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	ifrs-full_TypesOfSharebasedPaymentArrangementsAxis=fsm_PerformanceShareUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	ifrs-full_RangeAxis=ifrs-full_TopOfRangeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: