XML 144 R117.htm IDEA: XBRL DOCUMENT
v3.21.1

Income Taxes (Schedule of Tax Losses Expiry Dates) (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019
Income Taxes [line items] |  |
Unused tax losses for which no deferred tax asset recognised | $ 90,192 | $ 72,156
CANADA |  |
Income Taxes [line items] |  |
Unused tax losses for which no deferred tax asset recognised | $ 90,300 | $ 84,200
CANADA | Bottom of range [member] |  |
Income Taxes [line items] |  |
Year of Expiry | 2026 | 2026
CANADA | Top of range [member] |  |
Income Taxes [line items] |  |
Year of Expiry | 2040 | 2039
ARGENTINA |  |
Income Taxes [line items] |  |
Year of Expiry | 2021 |
Unused tax losses for which no deferred tax asset recognised | $ 68,900 | $ 42,500
ARGENTINA | Bottom of range [member] |  |
Income Taxes [line items] |  |
Year of Expiry |  | 2020
ARGENTINA | Top of range [member] |  |
Income Taxes [line items] |  |
Year of Expiry | 2025 | 2024
MEXICO |  |
Income Taxes [line items] |  |
Year of Expiry |  | 2029
Unused tax losses for which no deferred tax asset recognised | $ 367 | $ 369
MEXICO | Bottom of range [member] |  |
Income Taxes [line items] |  |
Year of Expiry | 2021 | 2021
MEXICO | Top of range [member] |  |
Income Taxes [line items] |  |
Year of Expiry | 2030 |
PERU |  |
Income Taxes [line items] |  |
Year of Expiry |  | 2021
Unused tax losses for which no deferred tax asset recognised |  | $ 70

X
- Definition Expiry year of tax loss carryforwards. + References No definition available. + Details
Name: | fsm_ExpiryYearOfTaxLossCarryforwards
Namespace Prefix: | fsm_
Data Type: | xbrli:gYearItemType
Balance Type: | na
Period Type: | duration

X
- Definition Income Taxes [line items]. + References No definition available. + Details
Name: | fsm_IncomeTaxesLineItems
Namespace Prefix: | fsm_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of unused tax losses for which no deferred tax asset is recognised in the statement of financial position. [Refer: Unused tax losses [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 12 -IssueDate 2020-01-01 -Paragraph 81 -Subparagraph e -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=12&code=ifrs-tx-2020-en-r&anchor=para_81_e&doctype=Standard -URIDate 2020-01-01 + Details
Name: | ifrs-full_UnusedTaxLossesForWhichNoDeferredTaxAssetRecognised
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | ifrs-full_GeographicalAreasAxis=country_CA
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_RangeAxis=ifrs-full_BottomOfRangeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | ifrs-full_GeographicalAreasAxis=country_AR
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_GeographicalAreasAxis=country_MX
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_GeographicalAreasAxis=country_PE
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |