Supplemental Information on Oil and Gas Exploration and Production Activities (Unaudited) - Capitalized Costs Related to Oil and Gas Producing Activities (Details) - USD ($) $ in Thousands |
Dec. 31, 2018 |
Dec. 31, 2017 |
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| Reserve Quantities [Line Items] | ||
| Proven properties | $ 7,153,799 | $ 6,256,182 |
| Unproven properties | 2,873,037 | 2,912,974 |
| Capitalized costs, gross | 10,026,836 | 9,169,156 |
| Accumulated depreciation, depletion, amortization and impairment reserve | (4,613,293) | (4,136,777) |
| Net capitalized costs | 5,413,543 | 5,032,379 |
| Investment in Grizzly Oil Sands ULC | ||
| Reserve Quantities [Line Items] | ||
| Proven properties | 67,475 | 73,818 |
| Unproven properties | 79,605 | 86,540 |
| Capitalized costs, gross | 147,080 | 160,358 |
| Accumulated depreciation, depletion, amortization and impairment reserve | (1,553) | (1,693) |
| Net capitalized costs | $ 145,527 | $ 158,665 |
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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 of accumulated depreciation, depletion, amortization and valuation allowance relating to oil and gas producing activities. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition The sum of capitalized costs relating to oil and gas producing activities before accounting for accumulated depreciation. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Net amount of capitalized costs relating to oil and gas producing activities. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Capitalized costs of proved properties incurred for any combination mineral interests acquisitions; wells and related equipment; support equipment and facilities; and uncompleted wells and equipment and other costs not previously disclosed within this table. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Capitalized costs of unproved properties incurred for any combination mineral interests acquisitions and other costs not previously disclosed within this table. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Details
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