Total power consumption by the company during the period

No definition available.

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Namespace Prefix:	gsm_
Data Type:	dtr-types:energyItemType
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Period Type:	duration

- Definition

The value of fixed energy price.

+ References

No definition available.

+ Details

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Namespace Prefix:	gsm_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

The amount of possible increase (Decrease) in profit and loss due to reasonably possible decrease in designated risk component.

+ References

No definition available.

+ Details

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Namespace Prefix:	gsm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount of possible increase (Decrease) in profit and loss due to reasonably possible increase in designated risk component.

+ References

No definition available.

+ Details

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Namespace Prefix:	gsm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The maximum units of energy that will be supplied under the agreement.

+ References

No definition available.

+ Details

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Namespace Prefix:	gsm_
Data Type:	dtr-types:energyItemType
Balance Type:	na
Period Type:	duration

- Definition

The total number PPA cancelled.

+ References

No definition available.

+ Details

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Namespace Prefix:	gsm_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

The total number PPA signed.

+ References

No definition available.

+ Details

Name:	gsm_NumberOfPpaSigned
Namespace Prefix:	gsm_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

The percentage of reasonable possible decrease in risk assumption.

+ References

No definition available.

+ Details

Name:	gsm_PercentageOfReasonablyPossibleDecreaseInRiskAssumption
Namespace Prefix:	gsm_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The percentage of reasonable possible increase in risk assumption.

+ References

No definition available.

+ Details

Name:	gsm_PercentageOfReasonablyPossibleIncreaseInRiskAssumption
Namespace Prefix:	gsm_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The term for which the energy will be supplied under the agreement.

+ References

No definition available.

+ Details

Name:	gsm_TermOfEnergySupply
Namespace Prefix:	gsm_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

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.

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
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Financial risk management - Power risk (Details) - Power Risk	1 Months Ended		12 Months Ended
	Jul. 31, 2024 € / MWh MWh	Dec. 31, 2023 item € / MWh GWh	Dec. 31, 2025 USD ($) item GWh	Dec. 31, 2024 € / MWh item GWh
Disclosure of nature and extent of risks arising from financial instruments [line items]
Total power consumption \| GWh			5,801	5,915
Maximum energy supply	150,000	285		130
Number Of PPA SIgned		2		5
Number Of PPA Cancelled				1
Fixed energy price \| € / MWh		50
Percentage Of Reasonably Possible Increase In Risk Assumption			10.00%
Percentage Of Reasonably Possible Decrease In Risk Assumption			10.00%
Increase in energy expenditure \| $			$ 22,706,000
Decrease in energy expenditure. \| $			$ 22,706,000
Term of energy supply		10 years
Power Purchase Agreement (PPA) \| Minimum
Disclosure of nature and extent of risks arising from financial instruments [line items]
Fixed energy price \| € / MWh	43			50
Power Purchase Agreement (PPA) \| Maximum
Disclosure of nature and extent of risks arising from financial instruments [line items]
Fixed energy price \| € / MWh	58			77
Supply To Sabon On A Pay As Produce Basis [Member]
Disclosure of nature and extent of risks arising from financial instruments [line items]
Number Of PPA SIgned		3
Number Of PPA Cancelled			1