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Environmental Trust Funds - Schedule of Environmental Trust Funds (Detail) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Environmental Trust Funds [abstract] |  |  |
Balance at beginning of the year | $ 69.5 | $ 60.8 |
Contributions | 8.7 | 7.1 |
Interest earned | 0.7 | 0.7 | $ 0.6
Translation adjustment | 0.4 | 0.9 |
Balance at end of the year | $ 79.3 | $ 69.5 | $ 60.8

X
- Definition The amount of contributions into funds intended to fund environmental rehabilitation obligations of the entity. + References No definition available. + Details
Name: | gfi_ContributionsEnvironmentalTrustFunds
Namespace Prefix: | gfi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- Definition The funds intended to fund environmental rehabilitation obligations of the entity and are not available for general purposes of the entity. + References No definition available. + Details
Name: | gfi_EnvironmentalTrustFunds
Namespace Prefix: | gfi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Definition Environmental trust fund. + References No definition available. + Details
Name: | gfi_EnvironmentalTrustFundsAbstract
Namespace Prefix: | gfi_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition The amount of interest earned on funds intended to fund environmental rehabilitation obligations of the entity. + References No definition available. + Details
Name: | gfi_InterestEarnedEnvironmentalTrustFund
Namespace Prefix: | gfi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The amount of exchange differences arising on funds intended to fund environmental rehabilitation obligations of the entity. + References No definition available. + Details
Name: | gfi_TranslationAdjustmentEnvironmentalTrustFund
Namespace Prefix: | gfi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration