Revenue (Revenues from Contracts with Customers) (Details) - USD ($) $ in Thousands |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2019 |
Jun. 30, 2018 |
Jun. 30, 2019 |
Jun. 30, 2018 |
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| Disaggregation of Revenue [Line Items] | ||||
| Carried interest recoupment | $ 733 | $ 705 | $ 1,440 | $ 1,356 |
| Royalties | (3,799) | (3,472) | (6,552) | (7,134) |
| Total revenue, net | 25,230 | 24,426 | 44,995 | 52,071 |
| Sales Under COSPA [Member] | ||||
| Disaggregation of Revenue [Line Items] | ||||
| Revenue from customer contracts | 20,949 | $ 27,193 | 42,760 | 55,656 |
| Gabonese Government Share Of Profit Oil [Member] | ||||
| Disaggregation of Revenue [Line Items] | ||||
| Revenue from customer contracts | $ 2,193 | |||
| Revenue not from customer contracts | $ 7,347 | $ 7,347 | ||
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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/disclosureRef
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- Definition Amount of revenue that is not accounted for under Topic 606. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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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/disclosureRef
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- Definition Amount of expense related to royalty payments under a contractual arrangement such as payment for mineral and drilling rights and use of technology or intellectual property. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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