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Fair Value Measurements Long-term Debt (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2015 | Jun. 30, 2015 | Dec. 31, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Unproved Oil and Gas Property, Successful Effort Method | $ 419,903 | $ 419,903 | $ 532,498
Disposal Group, Not Discontinued Operation, Loss (Gain) on Write-down | 66,000 | 99,900 |
6.625% Senior Notes Due 2019 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Long-term Debt, Fair Value | 0 | 0 | 350,018
6.50% Senior Notes Due 2021 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Long-term Debt, Fair Value | 362,250 | 362,250 | 343,000
6.125% Senior Notes Due 2022 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Long-term Debt, Fair Value | 621,000 | 621,000 | 556,500
6.50% Senior Notes Due 2023 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Long-term Debt, Fair Value | 412,000 | 412,000 | 379,000
5% Senior Notes Due 2024 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Long-term Debt, Fair Value | 471,250 | 471,250 | 435,000
5.625% Senior Notes Due 2025 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Long-term Debt, Fair Value | $ 493,850 | $ 493,850 | $ 0
Senior Notes [Member] | 6.625% Senior Notes Due 2019 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 6.625% | 6.625% |
Senior Notes [Member] | 6.50% Senior Notes Due 2021 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 6.50% | 6.50% |
Senior Notes [Member] | 6.125% Senior Notes Due 2022 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 6.125% | 6.125% |
Senior Notes [Member] | 6.50% Senior Notes Due 2023 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 6.50% | 6.50% |
Senior Notes [Member] | 5% Senior Notes Due 2024 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 5.00% | 5.00% |
Senior Notes [Member] | 5.625% Senior Notes Due 2025 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 5.625% | 5.625% |
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Unproved Oil and Gas Property, Successful Effort Method | $ 0 | $ 0 |

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- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Amount, before tax, of (gain) loss recognized for the (reversal of write-down) write-down to fair value, less cost to sell, of a disposal group. Excludes discontinued operations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=51719941&loc=d3e2941-110230 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=51824106&loc=d3e2443-110228 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585 + Details
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- Definition The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. + References No definition available. + Details
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- Definition Oil and Gas properties with unproved reserves under the successful effort method. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 14 -URI http://asc.fasb.org/extlink&oid=51678428&loc=d3e61926-109447 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -Glossary Unproved Properties -URI http://asc.fasb.org/extlink&oid=6527831 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 360 -Section 25 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=56951519&loc=d3e64746-109465 + Details
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