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Acquisitions and Divestitures - Additional Information (Detail) (USD $)
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0 Months Ended | 3 Months Ended | 9 Months Ended | 1 Months Ended | 9 Months Ended | 3 Months Ended | 9 Months Ended | 3 Months Ended | 9 Months Ended | 1 Months Ended | ||||
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Jul. 11, 2013
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Sep. 30, 2013
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Sep. 30, 2012
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Sep. 30, 2013
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Sep. 30, 2012
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Dec. 31, 2012
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Oct. 05, 2012
Newfield Properties
acre
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Sep. 30, 2013
Newfield Properties
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Sep. 30, 2013
Newfield Properties Post Acquisition
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Sep. 30, 2013
Newfield Properties Post Acquisition
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Sep. 30, 2012
Newfield Properties Post Acquisition
Maximum
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Sep. 30, 2012
Newfield Properties Post Acquisition
Maximum
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May 15, 2012
South Timbalier 41
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Sep. 26, 2013
West Delta Area Block Twenty Nine
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| Business Acquisition [Line Items] | ||||||||||||||
| Oil and natural gas properties and equipment - full cost method, amount excluded from amortization | $ 129,584,000 | $ 129,584,000 | $ 123,503,000 | $ 13,100,000 | ||||||||||
| Long-term debt | 1,052,984,000 | 1,052,984,000 | 1,087,611,000 | 205,700,000 | ||||||||||
| Effective interest rate | 7.70% | |||||||||||||
| Total cash paid for acquisition | (205,732,000) | (205,732,000) | ||||||||||||
| Number of federal offshore blocks | 78 | |||||||||||||
| Leasehold interest acres acquired, gross | 416,000 | |||||||||||||
| Leasehold interest acres acquired, net | 268,000 | |||||||||||||
| Adjustments to purchase price | 200,000 | |||||||||||||
| Revenues | 244,555,000 | 185,946,000 | 739,160,000 | 637,345,000 | 31,900,000 | 94,200,000 | ||||||||
| Lease operating expenses | 67,346,000 | 53,411,000 | 194,935,000 | 170,349,000 | 5,500,000 | 19,600,000 | ||||||||
| Depreciation, depletion, amortization and accretion | 104,143,000 | 77,462,000 | 312,911,000 | 251,894,000 | 14,700,000 | 41,100,000 | ||||||||
| Income tax expense (benefit) | 8,033,000 | (2,175,000) | 35,358,000 | 33,959,000 | 4,100,000 | 11,700,000 | ||||||||
| Net income | 14,194,000 | (1,471,000) | 63,208,000 | 55,315,000 | 7,600,000 | 21,800,000 | ||||||||
| Expenses associated with acquisition activities and transition activities | 100,000 | 100,000 | ||||||||||||
| Percentage of non-operating working interest sold | 40.00% | |||||||||||||
| Proceeds from sale of non-operating working interest | 30,500,000 | 16,500,000 | ||||||||||||
| Reversal of asset retirement obligation | 15,600,000 | 4,000,000 | 3,900,000 | |||||||||||
| Federal statutory income tax rate | 35.00% | 35.00% | ||||||||||||
| Adjustment for effective date to sell properties | $ 4,300,000 | |||||||||||||