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Long-Term Debt - Additional Information (Detail) (USD $)
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6 Months Ended | 6 Months Ended | 6 Months Ended | 6 Months Ended | |||||||||||
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Jun. 30, 2013
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Dec. 31, 2012
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Jun. 30, 2013
Credit Facility [Member]
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Dec. 31, 2012
Credit Facility [Member]
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Jun. 30, 2013
Credit Facility [Member]
Minimum [Member]
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Jun. 30, 2013
Credit Facility [Member]
Maximum [Member]
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Jun. 30, 2013
Senior Notes [Member]
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Jun. 11, 2013
Senior Notes [Member]
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Jun. 30, 2013
Debt Instrument Redemption Period [Member]
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Jun. 30, 2013
Interest rate calculation one [Member]
Credit Facility [Member]
Minimum [Member]
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Jun. 30, 2013
Interest rate calculation one [Member]
Credit Facility [Member]
Maximum [Member]
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Jun. 30, 2013
Interest rate calculation two [Member]
Credit Facility [Member]
Minimum [Member]
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Jun. 30, 2013
Interest rate calculation two [Member]
Credit Facility [Member]
Maximum [Member]
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Jun. 30, 2013
Covenants agreements one [Member]
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Jun. 30, 2013
Covenants agreements two [Member]
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| Credit Facilities [Line Items] | |||||||||||||||
| Maturity period of revolving credit facility | Jul. 31, 2016 | Jul. 31, 2016 | |||||||||||||
| Revolving credit facility, borrowing base | $ 315,000,000 | ||||||||||||||
| Revolving credit facility, maximum borrowing capacity | 500,000,000 | ||||||||||||||
| Revolving credit facility, interest rate description | Borrowings bear interest based on the agent bank's prime rate plus an applicable margin ranging from 0.75% to 1.75%, or the sum of the Eurodollar rate plus an applicable margin ranging from 1.75% to 2.75%. | ||||||||||||||
| Revolving credit facility, marginal percentage | 0.75% | 1.75% | 1.75% | 2.75% | |||||||||||
| Annual commitment fee of unused borrowings | 0.50% | ||||||||||||||
| Increase in the borrowing base for line of credit facility | 280,000,000 | 315,000,000 | |||||||||||||
| Increased lender's aggregate maximum commitment | 300,000,000 | 500,000,000 | |||||||||||||
| Amount outstanding under revolving credit facility | 106,000,000 | 0 | 106,000,000 | ||||||||||||
| Interest rate applicable of revolving credit facility | 2.70% | ||||||||||||||
| Unused letters of credit outstanding | 325,000 | ||||||||||||||
| Consolidated current assets ratio | 1.0 | ||||||||||||||
| Consolidated current liabilities ratio | 1.0 | ||||||||||||||
| Covenant description | A consolidated modified current ratio covenant that requires us to maintain a ratio of not less than 1.0 to 1.0 at all times. | ||||||||||||||
| Consolidated funded debt ratio | 4.0 | ||||||||||||||
| Consolidated earnings before interest taxes depreciation amortization and exploration expenses ratio | 1.0 | ||||||||||||||
| Ratio covenant description | A consolidated funded debt-to-consolidated EBITDAX ratio covenant that requires us to maintain a ratio of not more than 4.0 to 1.0 at the end of each fiscal quarter. | ||||||||||||||
| Debt default description | In addition, our Credit Facility contains customary events of default that would permit our lenders to accelerate the debt under our Credit Facility if not cured within applicable grace periods, including, among others, failure to make payments of principal or interest when due, materially incorrect representations and warranties, failure to make mandatory prepayments in the event of borrowing base deficiencies, breach of covenants, defaults upon other obligations in excess of $500,000, events of bankruptcy, the occurrence of one or more unstayed judgments in excess of $500,000 not covered by an acceptable policy of insurance, failure to pay any obligation in excess of $500,000 owed under any derivatives transaction or in any amount if the obligation under the derivatives transaction is secured by collateral under the Credit Facility, any event of default by the Company occurs under any agreement entered into in connection with a derivatives transaction, liens securing the loans under the credit agreement cease to be in place, a change in control (as defined under the Credit Facility) of the Company occurs, and dissolution of the Company. | ||||||||||||||
| Debt default amount | 500,000 | ||||||||||||||
| Senior Notes maturity date | Jun. 15, 2021 | ||||||||||||||
| Senior Note | 250,000,000 | ||||||||||||||
| Stated interest rate | 7.00% | ||||||||||||||
| Issuance of Senior Notes | $ 242,746,000 | $ 243,000,000 | |||||||||||||
| Debt instrument, redemption description | Before June 15, 2016, we may redeem up to 35% of the Senior Notes at a redemption price of 107% of the principal amount, plus accrued and unpaid interest to the redemption date, with the proceeds of certain equity offerings. | ||||||||||||||
| Debt instrument, redemption percentage | 35.00% | ||||||||||||||
| Debt instrument, redemption of principal amount percentage | 100.00% | 107.00% | |||||||||||||