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Divestitures, Assets Held for Sale, and Acquisitions Divestitures and Assets Held for Sale (Details) - USD ($) $ in Thousands | 3 Months Ended |
--- | --- | ---
Mar. 31, 2017 | Mar. 31, 2016 | Dec. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |
Net proceeds from the sale of oil and gas properties |  | $ 744,333 | $ 1,206 |
Net gain (loss) on divestiture activity |  | 37,463 | (69,021) |
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest |  | 118,940 | (542,085) |
Impairment of Proved Oil and Gas Properties |  | $ 0 | 269,785 |
Assets Held-for-sale Reasonably Certain Period for Sale |  | 1 year |  |
Disposal Group, Including Discontinued Operation, Assets, Current |  | $ 455,943 |  | $ 372,621
Asset retirement obligation associated with oil and gas properties held for sale |  | 16,056 |  | $ 26,241
Abandonment and impairment of unproved properties |  | 0 | 2,311 |
Non-Operated Eagle Ford Divestiture 2017 [Member] |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |
Net proceeds from the sale of oil and gas properties |  | 747,400 |  |
Net gain (loss) on divestiture activity |  | 398,100 |  |
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Non-Operated Eagle Ford Divestiture 2017 [Member] |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest | [1] | 24,324 | (286,399) |
Impairment of Proved Oil and Gas Properties |  |  | 269,600 |
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Divide County Divestiture 2017 [Member] |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest | [2] | (335,561) | (16,813) |
Impairment of Proved Oil and Gas Properties |  | $ 359,600 |  |
Abandonment and impairment of unproved properties |  |  | $ 1,600 |
[1] | Income (loss) before income taxes reflects oil, gas, and NGL production revenue, less oil, gas, and NGL production expense and depletion, depreciation, amortization, and asset retirement obligation liability accretion. Additionally, income (loss) before income taxes included impairment of proved properties expense of approximately $269.6 million for the three months ended March 31, 2016.
[2] | Loss before income taxes reflects oil, gas, and NGL production revenue less oil, gas, and NGL production expense and depletion, depreciation, amortization, and asset retirement obligation liability accretion. Additionally, loss before income taxes for the three months ended March 31, 2017, included the $359.6 million write-down on these assets held for sale as discussed above, and loss before income taxes for the three months ended March 31, 2016, included $1.6 million of unproved property impairments.

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- Definition Noncurrent portion of the carrying amount of a liability for an asset retirement obligation for an asset held for sale. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees. + References No definition available. + Details
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- Definition Amount classified as assets attributable to disposal group held for sale or disposed of, expected to be disposed of within one year or the normal operating cycle, if longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 45 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=65878427&loc=d3e1107-107759 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=65878427&loc=SL51721533-107759 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=64862545&loc=d3e2941-110230 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 50 -Paragraph 5B -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721673-107760 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 9 -URI http://asc.fasb.org/extlink&oid=68055307&loc=d3e2473-110228 + Details
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