XML 119 R102.htm IDEA: XBRL DOCUMENT
v3.19.1

Provisions - Employee obligations - South Africa - (Details) - South Africa $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($)
Changes in net defined benefit liability (asset) [abstract] |  |
Percentage change in cost of medical aid | 1 | 1
Change in provision due to reasonably possible change in the cost of medical aid | $ 216 | $ 297
Disclosure of fair value of plan assets [abstract] |  |
Cash | 1.72% | 47.45%
Equity | 47.42% | 24.79%
Bonds | 13.62% | 7.66%
Property | 2.67% | 1.41%
International | 30.27% | 15.74%
Others | 4.30% | 2.95%
Total | 100.00% | 100.00%
Present value of defined benefit obligation [member] |  |
Changes in net defined benefit liability (asset) [abstract] |  |
Obligations at beginning of year | $ 7,872 | $ 8,760
Current service cost | 139 | 310
Borrowing costs | 740 | 932
Actuarial differences | (2,000) | (2,226)
Benefits paid | (226) | (740)
Exchange differences | (1,096) | 836
Obligations at end of year | 5,429 | 7,872
Plan assets [member] |  |
Ifrs Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward] |  |
Fair value of plan assets at the beginning of the year | 2,248 | 3,532
Interest income on assets | 216 | 255
Benefits paid | (50) | (2,609)
Actuarial differences | (228) | 270
Other | (280) | 800
Fair value of plan assets at the end of the year | 1,906 | 2,248
Actual return on assets | $ (11) | $ 525

X
- Definition The amount that instruments representing bonds constitute of the fair value of defined benefit plan assets as a percent of total defined benefit plan assets. + References No definition available. + Details
Name: | gsm_BondsAmountContributedToFairValueOfPlanAssetsAsPercentOfTotalDefinedBenefitPlanAssets
Namespace Prefix: | gsm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount that cash and cash equivalents constitute of the fair value of defined benefit plan assets as a percent of total defined benefit plan assets. + References No definition available. + Details
Name: | gsm_CashAndCashEquivalentsAmountContributedToFairValueOfPlanAssetsAsPercentOfTotalDefinedBenefitPlanAssets
Namespace Prefix: | gsm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The increase in defined benefit plan assets due to interest income. + References No definition available. + Details
Name: | gsm_DefinedBenefitPlanInterestIncomeOnPlanAssets
Namespace Prefix: | gsm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Represents the percentage of fair value of plan assets. + References No definition available. + Details
Name: | gsm_DisclosureOfFairValueOfPlanAssetsAsPercentage
Namespace Prefix: | gsm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount that instruments representing equity (rather than debt) constitute of the fair value of defined benefit plan assets as a percent of total defined benefit plan assets. + References No definition available. + Details
Name: | gsm_EquityInstrumentsAmountContributedToFairValueOfPlanAssetsAsPercentOfTotalDefinedBenefitPlanAssets
Namespace Prefix: | gsm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The difference between fair value of plan assets at the end of the period and the fair value at the beginning of the period, adjusted for contributions and payments of benefits during the period, and after adjusting for taxes and other expenses, as applicable. + References No definition available. + Details
Name: | gsm_IfrsDefinedBenefitPlanActualReturnOnPlanAssets
Namespace Prefix: | gsm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The amount of payments made for which participants are entitled under a pension plan, including pension benefits, death benefits, and benefits due on termination of employment. Also includes payments made under a postretirement benefit plan, including prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services. This item represents a periodic decrease to the plan obligations and a decrease to plan assets. + References No definition available. + Details
Name: | gsm_IfrsDefinedBenefitPlanBenefitsPaid
Namespace Prefix: | gsm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
Name: | gsm_IfrsDefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward
Namespace Prefix: | gsm_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The increase (decrease) in a defined benefit obligation that would have been caused by a change in cost of medical aid that was reasonably possible at the end of the reporting period. + References No definition available. + Details
Name: | gsm_IncreaseDecreaseInDefinedBenefitObligationDueToReasonablyPossibleChangeInCostOfMedicalAid
Namespace Prefix: | gsm_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Increase (decrease) in defined benefit plan assets due to changes in actuarial assumptions. + References No definition available. + Details
Name: | gsm_IncreaseDecreaseInDefinedBenefitPlanAssetsDueToActuarialDifferences
Namespace Prefix: | gsm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Increase (decrease) in defined plan assets due to other reasons not specifically disclosed. + References No definition available. + Details
Name: | gsm_IncreaseDecreaseInDefinedBenefitPlanAssetsDueToOther
Namespace Prefix: | gsm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The amount that international investments constitutes of the fair value of defined benefit plan assets as a percent of total defined benefit plan assets. + References No definition available. + Details
Name: | gsm_InternationalInvestmentsAmountContributedToFairValueOfPlanAssetsAsPercentOfTotalDefinedBenefitPlanAssets
Namespace Prefix: | gsm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount that other types of assets not separately disclosed constitute of the fair value of defined benefit plan assets as a percent of total defined benefit plan assets. + References No definition available. + Details
Name: | gsm_OtherAssetsAmountContributedToFairValueOfPlanAssetsAsPercentOfTotalDefinedBenefitPlanAssets
Namespace Prefix: | gsm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The reasonably possible percentage of the change in the cost of medical aid used to determine the defined benefit obligation. + References No definition available. + Details
Name: | gsm_PercentageOfReasonablyPossibleChangeInCostOfMedicalAid
Namespace Prefix: | gsm_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

X
- Definition The amount that real estate constitutes of the fair value of defined benefit plan assets as a percent of total defined benefit plan assets. + References No definition available. + Details
Name: | gsm_RealEstateAmountContributedToFairValueOfPlanAssetsAsPercentOfTotalDefinedBenefitPlanAssets
Namespace Prefix: | gsm_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | ifrs-full_ChangesInNetDefinedBenefitLiabilityAssetAbstract
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The increase (decrease) in the net defined benefit liability (asset) resulting from employee service in the current period. [Refer: Net defined benefit liability (asset)] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2018-01-01 -Paragraph 141 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2018-03-01&anchor=para_141_a&doctype=Standard -URIDate 2018-03-16 + Details
Name: | ifrs-full_CurrentServiceCostNetDefinedBenefitLiabilityAsset
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- References No definition available. + Details
Name: | ifrs-full_DisclosureOfFairValueOfPlanAssetsAbstract
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The decrease (increase) in a net defined benefit liability (asset) resulting from the remeasurement of that net defined benefit liability (asset). [Refer: Net defined benefit liability (asset)] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2018-01-01 -Paragraph 141 -Subparagraph c -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2018-03-01&anchor=para_141_c&doctype=Standard -URIDate 2018-03-16 + Details
Name: | ifrs-full_GainLossOnRemeasurementOfNetDefinedBenefitLiabilityAsset
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The increase (decrease) in the net defined benefit liability (asset) resulting from changes in foreign exchange rates. [Refer: Net defined benefit liability (asset)] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2018-01-01 -Paragraph 141 -Subparagraph e -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2018-03-01&anchor=para_141_e&doctype=Standard -URIDate 2018-03-16 + Details
Name: | ifrs-full_IncreaseDecreaseThroughChangesInForeignExchangeRatesNetDefinedBenefitLiabilityAsset
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The increase (decrease) in the net defined benefit liability (asset) resulting from the passage of time. [Refer: Interest expense; Net defined benefit liability (asset)] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2018-01-01 -Paragraph 141 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2018-03-01&anchor=para_141_b&doctype=Standard -URIDate 2018-03-16 + Details
Name: | ifrs-full_InterestExpenseIncomeNetDefinedBenefitLiabilityAsset
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The amount of deficit or surplus in a defined benefit plan, adjusted for any effect of limiting a net defined benefit asset to the asset ceiling. [Refer: Defined benefit plans [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2018-01-01 -Paragraph 140 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2018-03-01&anchor=para_140_a&doctype=Standard -URIDate 2018-03-16 + Details
Name: | ifrs-full_LiabilityAssetOfDefinedBenefitPlans
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The decrease (increase) in the net defined benefit liability (asset) resulting from payments from the plan. [Refer: Net defined benefit liability (asset)] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2018-01-01 -Paragraph 141 -Subparagraph g -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2018-03-01&anchor=para_141_g&doctype=Standard -URIDate 2018-03-16 + Details
Name: | ifrs-full_PaymentsFromPlanNetDefinedBenefitLiabilityAsset
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The fair value of defined benefit plan assets. Plan assets comprise assets held by a long-term employee benefit fund and qualifying insurance policies. [Refer: At fair value [member]] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 19 -IssueDate 2018-01-01 -Paragraph 57 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2018-03-01&anchor=para_57_a&doctype=Standard -URIDate 2018-03-16 + Details
Name: | ifrs-full_PlanAssetsAtFairValue
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

X
- Details
Name: | ifrs-full_NetDefinedBenefitLiabilityAssetAxis=ifrs-full_PresentValueOfDefinedBenefitObligationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_NetDefinedBenefitLiabilityAssetAxis=ifrs-full_PlanAssetsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |