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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) | 12 Months Ended
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Dec. 31, 2016
Minimum |
Property, Plant and Equipment [Line Items] |
Useful life (in years) | 3 years
Maximum |
Property, Plant and Equipment [Line Items] |
Useful life (in years) | 15 years
Buildings |
Property, Plant and Equipment [Line Items] |
Useful life (in years) | 15 years
Shop tools and equipment | Minimum |
Property, Plant and Equipment [Line Items] |
Useful life (in years) | 3 years
Shop tools and equipment | Maximum |
Property, Plant and Equipment [Line Items] |
Useful life (in years) | 5 years
Mining equipment |
Property, Plant and Equipment [Line Items] |
Useful life (in years) | 5 years
Office equipment | Minimum |
Property, Plant and Equipment [Line Items] |
Useful life (in years) | 4 years
Office equipment | Maximum |
Property, Plant and Equipment [Line Items] |
Useful life (in years) | 5 years
Furniture and fixtures | Minimum |
Property, Plant and Equipment [Line Items] |
Useful life (in years) | 5 years
Furniture and fixtures | Maximum |
Property, Plant and Equipment [Line Items] |
Useful life (in years) | 7 years
Light trucks & utility vehicles |
Property, Plant and Equipment [Line Items] |
Useful life (in years) | 5 years
Nichols Ranch Project |
Property, Plant and Equipment [Line Items] |
Useful life (in years) | 12 years
Alta Mesa |
Property, Plant and Equipment [Line Items] |
Useful life (in years) | 15 years

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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
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
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Period Type: | duration

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- Definition Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment. + References No definition available. + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

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- Details
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Namespace Prefix: |
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Balance Type: |
Period Type: |

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | us-gaap_BusinessAcquisitionAxis=efr_NicholsRanchProjectMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | us-gaap_BusinessAcquisitionAxis=efr_AltaMesaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |