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Asset Retirement Obligations (Narrative) (Details) - USD ($) $ in Thousands | 1 Months Ended | 12 Months Ended
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Dec. 31, 2019 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Asset Retirement Obligations [Abstract] |  |  |  |
Asset retirement obligation, revision of estimate | $ (400) | $ (379) | $ (6,527) | $ 703

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- References No definition available. + Details
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- Definition Amount of increase (decrease) in the asset retirement obligation from changes in the amount or timing of the estimated cash flows associated with the settlement of the obligation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 35 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=6392603&loc=d3e7123-110846 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c)(4) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
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