Revenue (Revenues From Contracts With Customers) (Details) - USD ($) $ in Thousands |
3 Months Ended | |
|---|---|---|
Mar. 31, 2018 |
Mar. 31, 2017 |
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| Disaggregation of Revenue [Line Items] | ||
| Revenue | $ 27,645 | $ 21,266 |
| Glencore Oil Revenue [Member] | ||
| Disaggregation of Revenue [Line Items] | ||
| Revenue from customer contracts | 28,463 | 20,344 |
| Gabonese Government Share Of Profit Oil [Member] | ||
| Disaggregation of Revenue [Line Items] | ||
| Revenue from customer contracts | 2,193 | 3,194 |
| U.S. Oil And Gas Revenue [Member] | ||
| Disaggregation of Revenue [Line Items] | ||
| Revenue from customer contracts | 20 | |
| Carried Interest Recoupment [Member] | ||
| Disaggregation of Revenue [Line Items] | ||
| Other items reported in revenue not associated with customer contracts | 651 | 817 |
| Royalties [Member] | ||
| Disaggregation of Revenue [Line Items] | ||
| Other items reported in revenue not associated with customer contracts | $ (3,662) | $ (3,109) |
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- Definition Revenues, Not Associated With Customer Contracts No definition available.
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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. No definition available.
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- Definition Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss). Reference 1: http://www.xbrl.org/2003/role/presentationRef
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