|
Acquisitions and Divestitures (Narrative) (Detail) (USD $)
|
0 Months Ended | 3 Months Ended | 9 Months Ended | 12 Months Ended | 3 Months Ended | 9 Months Ended | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|
|
Jun. 15, 2012
|
Sep. 30, 2012
acre
|
Sep. 30, 2011
|
Sep. 30, 2012
acre
|
Sep. 30, 2011
|
Sep. 30, 2012
acre
|
May 11, 2011
Yellow Rose Properties [Member]
acre
|
Sep. 30, 2012
Fairway Properties [Member]
|
Aug. 10, 2012
Fairway Properties [Member]
|
Sep. 30, 2011
Yellow Rose Properties and Fairway Properties [Member]
|
Sep. 30, 2011
Yellow Rose Properties and Fairway Properties [Member]
|
|
| Business Acquisition [Line Items] | |||||||||||
| Percentage of non-operating working interest sold | 40.00% | ||||||||||
| Proceeds from sale of non-operating working interest | $ 30,500,000 | ||||||||||
| Reversal of asset retirement obligation | 4,000,000 | ||||||||||
| Number of acres of oil and gas leasehold interests acquired, gross | 432,700 | 432,700 | 432,700 | 24,500 | |||||||
| Number of acres of oil and gas leasehold interests acquired, net | 21,900 | ||||||||||
| Percentage of working interest include in producing interest | 64.30% | ||||||||||
| Purchase price reduced | 2,700,000 | ||||||||||
| Revenue | 185,946,000 | 245,371,000 | 637,345,000 | 709,148,000 | 21,600,000 | 32,800,000 | |||||
| Direct operating expenses | 8,800,000 | 10,700,000 | |||||||||
| Depreciation, depletion, amortization and accretion | 77,462,000 | 84,455,000 | 251,894,000 | 241,917,000 | 7,200,000 | 9,600,000 | |||||
| Income taxes | (2,175,000) | 28,822,000 | 33,959,000 | 68,841,000 | 2,000,000 | 4,400,000 | |||||
| Net income | (1,471,000) | 52,928,000 | 55,315,000 | 126,752,000 | 3,600,000 | 8,100,000 | |||||
| Expenses associated with acquisition activities and transition activities | 800,000 | 1,400,000 | |||||||||
| Purchase price allocation of unevaluated properties for oil and gas interests | 82,600,000 | 82,600,000 | |||||||||
| Incremental transaction expenses related to acquisitions | $ 800,000 | $ 1,400,000 | |||||||||
| Business acquisition debt instrument, interest rate, minimum | 3.10% | ||||||||||
| Business acquisition debt instrument, interest rate, maximum | 3.50% | ||||||||||
| Federal statutory income tax rate | 35.00% | 35.00% | |||||||||
| X | ||||||||||
|
- Details
|
| X | ||||||||||
|
- Definition
The amount of acquisition cost of a business combination allocated to property, plant and equipment to be used in ongoing operations. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Definition
This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Definition
The expenses and losses recorded for each transaction with the acquiree that was recognized separately from the acquisition of assets and assumptions of liabilities in the business combination. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Definition
The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Definition
The aggregate direct operating costs incurred during the reporting period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Definition
The domestic federal statutory tax rate applicable under enacted tax laws to the Company's pretax income from continuing operations for the period. The "statutory" tax rate is the regular tax rate if there are alternative tax systems. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Definition
The sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to continuing operations. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Definition
The portion of profit or loss for the period, net of income taxes, which is attributable to the parent. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Definition
Aggregate revenue recognized during the period (derived from goods sold, services rendered, insurance premiums, or other activities that constitute an entity's earning process). For financial services companies, also includes investment and interest income, and sales and trading gains. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Definition
Asset Retirement Obligation Reversal Related To Sale Of Facilities No definition available.
|
| X | ||||||||||
|
- Definition
Business Acquisition Debt Instrument, Interest Rate, Maximum. No definition available.
|
| X | ||||||||||
|
- Definition
Business Acquisition Debt Instrument, Interest Rate, Minimum. No definition available.
|
| X | ||||||||||
|
- Definition
Business Acquisition Purchase Price Adjustment No definition available.
|
| X | ||||||||||
|
- Definition
Non-Operating Working Interest, Percentage Sold No definition available.
|
| X | ||||||||||
|
- Definition
Number Of Acres Of Oil And Gas Leasehold Interests Acquired, Gross No definition available.
|
| X | ||||||||||
|
- Definition
Number Of Acres Of Oil And Gas Leasehold Interests Acquired, Net No definition available.
|
| X | ||||||||||
|
- Definition
Percentage Of Working Interest Include In Producing Interest No definition available.
|
| X | ||||||||||
|
- Definition
Proceed From Sale Of Non-Operating Working Interest No definition available.
|