Supplemental Oil and Gas Disclosures - Cost Incurred in Oil and Gas Property Acquisition Exploration and Development Activities (Details) - USD ($) $ in Millions |
12 Months Ended | |||||||||
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Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
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| Costs incurred: | ||||||||||
| Proved properties acquisitions | [1] | $ 1.1 | $ 1.3 | $ 15.6 | ||||||
| Exploration | [1],[2],[3] | 62.0 | 4.8 | 152.4 | ||||||
| Development | [1] | 92.5 | 56.9 | 65.5 | ||||||
| Unproved property acquisitions | [1] | 0.5 | 0.1 | |||||||
| Total costs incurred in oil and gas property acquisition, exploration and development activities | [1] | $ 155.6 | $ 63.5 | $ 233.6 | ||||||
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- Definition Costs incurred, including capitalized costs and costs charged to expense, associated with the acquisition of oil and gas properties that have proved reserves. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Costs incurred, including capitalized costs and costs charged to expense, associated with the acquisition of oil and gas properties that have unproved reserves. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Development costs incurred, including capitalized costs and costs charged to expense, in oil and gas activities. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Exploration costs incurred, including capitalized costs and costs charged to expense, in oil and gas activities. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Amount of costs incurred related to oil and gas property acquisition, exploration and development activities, including capitalized costs and costs charged to expense. No definition available.
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- References No definition available.
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