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Property and Equipment (Summary of Non-producing Properties Excluded from Amortization by Area) (Details) - USD ($) $ in Thousands | Sep. 30, 2017 | Dec. 31, 2016
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Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items] |  |
Total non-producing properties not subject to amortization | $ 2,956,732 | $ 1,580,305
Utica |  |
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items] |  |
Total non-producing properties not subject to amortization | 1,517,555 |
MidContinent |  |
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items] |  |
Total non-producing properties not subject to amortization | 1,435,992 |
Niobrara |  |
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items] |  |
Total non-producing properties not subject to amortization | 2,182 |
Southern Louisiana |  |
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items] |  |
Total non-producing properties not subject to amortization | 536 |
Bakken |  |
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items] |  |
Total non-producing properties not subject to amortization | 99 |
Other |  |
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items] |  |
Total non-producing properties not subject to amortization | $ 368 |

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- Definition The sum of the capitalized costs incurred, as of the balance sheet date, of unproved properties excluded from amortization including acquisition costs, exploration costs, development costs, and production costs. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-10.(c)(7)(ii)) -URI http://asc.fasb.org/extlink&oid=82851474&loc=d3e511914-122862 + Details
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