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v3.5.0.2

Fair Value Measurements - Additional Information (Details) - USD ($) | 3 Months Ended | 6 Months Ended | 12 Months Ended
--- | --- | --- | ---
Jun. 30, 2016 | Jun. 30, 2015 | Jun. 30, 2016 | Jun. 30, 2015 | Dec. 31, 2015
Debt Instrument [Line Items] |  |  |  |  |
Derivative credit risk valuation adjustment, derivative assets | $ 2,400,000 |  | $ 2,400,000 |  | $ 300,000
Long-term debt | 2,127,361,000 |  | 2,127,361,000 |  | 2,302,584,000
Deferred financing costs | 36,700,000 |  | 36,700,000 |  |
Asset retirement obligation, carrying value | 37,128,000 |  | 37,128,000 |  | 35,812,000
Impairment | 23,000 | $ 19,516,000 | 3,585,000 | $ 24,837,000 |
Proved Oil and Gas Properties [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Impairment | 0 | 0 | 0 | 0 |
Proved Oil and Gas Properties [Member] | Assets disposed of by sale [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Impairment |  |  | 3,600,000 |  |
Proved Oil and Gas Properties [Member] | Assets disposed of by sale [Member] | Operating Segments [Member] | Midstream Services [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Impairment |  |  | 2,400,000 |  |
Proved Oil and Gas Properties [Member] | Assets disposed of by sale [Member] | Operating Segments [Member] | Exploration and Production [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Impairment |  |  | 1,200,000 |  |
Proved Oil and Gas Properties [Member] | Assets held for sale [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Impairment |  |  |  |  | $ 9,400,000
Unproved Oil And Gas Properties [Member] | Expiring Lease 1 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Impairment | 23,000 | 400,000 | 25,000 | 4,500,000 |
Unproved Oil And Gas Properties [Member] | Expiring Lease 2 [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Impairment |  | $ 19,100,000 |  | $ 20,300,000 |
Senior Unsecured Debt [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Long-term debt, fair value | 1,965,200,000 |  | 1,965,200,000 |  |
Line of Credit [Member] | Revolving Credit Facility [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Line of credit facility, amount outstanding | 35,000,000 |  | 35,000,000 |  |
Long-term Debt [Member] | Notes [Member] | Senior Unsecured Debt [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Long-term debt | 2,123,400,000 |  | 2,123,400,000 |  |
Deferred financing costs | $ 31,000,000 |  | $ 31,000,000 |  |

X
- Definition The carrying amount of a liability for an asset retirement obligation. 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 Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Asset Retirement Obligation -URI http://asc.fasb.org/extlink&oid=6505190 + Details
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- Definition Amount, after accumulated amortization, of debt issuance costs classified as noncurrent. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28555-108399 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.17) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition The expense recorded to reduce the value of oil and gas assets consisting of proved properties and unproved properties as the estimate of future successful production from these properties is reduced. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=64862545&loc=d3e2921-110230 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 360 -Section 35 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=66906256&loc=d3e66150-109466 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=66902209&loc=d3e3602-108585 + Details
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- Definition The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the 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)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(16)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + 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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