Subsequent Events (Details) - Subsequent Event - USD ($) $ in Millions |
1 Months Ended | 3 Months Ended |
|---|---|---|
Apr. 30, 2018 |
Jun. 30, 2018 |
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| Subsequent Event [Line Items] | ||
| Sale of Australian exploration permit | $ 0.0 | |
| Release of liabilities from canceled seismic survey | $ 1.3 | |
| Loss on sale of Australian exploration permit | $ 1.0 |
| X | ||||||||||
- Definition Increase (Decrease) in Exploration Liabilities No definition available.
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| X | ||||||||||
- Definition Amount of gain (loss) on sale or disposal of intangible assets. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
- Definition The cash inflow from disposal of asset without physical form usually arising from contractual or other legal rights, excluding goodwill. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
- Definition Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event. No definition available.
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| X | ||||||||||
- Details
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