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COMMITMENTS AND CONTINGENCIES - Supply Commitment (Details) lb in Thousands | Dec. 31, 2016 lb
--- | ---
Spot Contract |
Supply Commitment [Line Items] |
2017 | 200,000
2018 | 200,000
Long-Term Contract |
Supply Commitment [Line Items] |
2017 | 320,000
2018 | 200,000
2019 | 100,000
2020 | 100,000

X
- Definition Supply Commitment, Due in Fourth Year + References No definition available. + Details
Name: | efr_SupplyCommitmentDueinFourthYear
Namespace Prefix: | efr_
Data Type: | num:massItemType
Balance Type: | na
Period Type: | instant

X
- Definition Supply Commitment, Due in Next Fiscal Year + References No definition available. + Details
Name: | efr_SupplyCommitmentDueinNextFiscalYear
Namespace Prefix: | efr_
Data Type: | num:massItemType
Balance Type: | na
Period Type: | instant

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- Definition Supply Commitment, Due in Second Year + References No definition available. + Details
Name: | efr_SupplyCommitmentDueinSecondYear
Namespace Prefix: | efr_
Data Type: | num:massItemType
Balance Type: | na
Period Type: | instant

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- Definition Supply Commitment, Due in Third Year + References No definition available. + Details
Name: | efr_SupplyCommitmentDueinThirdYear
Namespace Prefix: | efr_
Data Type: | num:massItemType
Balance Type: | na
Period Type: | instant

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_SupplyCommitmentLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Details
Name: | us-gaap_SupplyCommitmentAxis=efr_U3O8SpotContractSupplyCommitmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | us-gaap_SupplyCommitmentAxis=efr_U3O8LongTermContractSupplyCommitmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |