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Supplemental Oil and Gas Disclosures - Additional Information (Detail) - USD ($) $ in Millions | Dec. 31, 2018 | Dec. 31, 2017
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Proved oil and gas properties |  |
Oil and Gas Delivery Commitments and Contracts [Line Items] |  |
Asset retirement costs | $ 40.5 | $ 38.4

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- Definition The amount of asset retirement costs previously incurred and capitalized separately from the capitalized amount of the associated long-lived assets. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 13 -URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e61901-109447 + Details
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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. + References No definition available. + Details
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- Details
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