XML 54 R38.htm IDEA: XBRL DOCUMENT
v3.10.0.1

ASSET RETIREMENT OBLIGATIONS AND RESTRICTED CASH - Narrative (Details) - USD ($) $ in Thousands | 6 Months Ended |  |
--- | --- | --- | ---
Jun. 30, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Schedule of Asset Retirement Obligations [Line Items] |  |  |
Inflation rate | 2.00% |  |
Asset retirement obligation | $ 19,046 | $ 18,280 | $ 17,033
Minimum |  |  |
Schedule of Asset Retirement Obligations [Line Items] |  |  |
Fair value assumptions, risk free interest rate | 9.50% |  |
Maximum |  |  |
Schedule of Asset Retirement Obligations [Line Items] |  |  |
Fair value assumptions, risk free interest rate | 11.50% |  |
Canyon Project |  |  |
Schedule of Asset Retirement Obligations [Line Items] |  |  |
Asset retirement obligation | $ 43,310 | $ 43,460 |

X
- Definition Inflation rate + References No definition available. + Details
Name: | efr_InflationRate
Namespace Prefix: | efr_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition [Line Items] for Schedule of Asset Retirement Obligations [Table] + References No definition available. + Details
Name: | efr_ScheduleofAssetRetirementObligationsLineItems
Namespace Prefix: | efr_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
Name: | us-gaap_AssetRetirementObligation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Risk-free interest rate assumption used in valuing an instrument. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueAssumptionsRiskFreeInterestRate
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LossContingenciesByNatureOfContingencyAxis=efr_CanyonProjectMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |