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Long-Term Debt - Additional Information (Detail) |  | 12 Months Ended | 24 Months Ended |  |  |
--- | --- | --- | --- | --- | --- | ---
Apr. 13, 2015 USD ($) | Dec. 31, 2015 USD ($) financial_institution | Dec. 31, 2014 USD ($) | Dec. 31, 2013 USD ($) | Dec. 31, 2012 USD ($) | Oct. 06, 2015 USD ($) | Oct. 05, 2015 USD ($) | Apr. 12, 2015 USD ($)
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Ownership percentage, Guarantors |  | 100.00% |  |  |  |  |  |
Number of financial institutions | financial_institution |  | 18 |  |  |  |  |  |
Collateral, percent of reserve value required |  | 80.00% |  |  |  |  |  |
Deferred financing costs |  | $ 42,900,000 |  |  |  |  |  |
Amortization of deferred financing costs |  | 7,200,000 | $ 6,400,000 | $ 4,500,000 |  |  |  |
Accounting Standards Update 2015-03 | Long-term debt |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Deferred financing costs |  | $ (35,400,000) |  |  |  |  |  |
Unsecured debt |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Redemption term |  | 180 days |  |  |  |  |  |
Default in payment of interest, term |  | 30 days |  |  |  |  |  |
Event of default by final judgments, payment term |  | 60 days |  |  |  |  |  |
Revolving credit facility |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Line of credit facility, capacity available for specific purpose other than for trade purchases |  | $ 2,500,000,000.0 |  |  |  |  |  |
Extension of maturity date condition, retirement or refinancing of note, term | 90 days |  |  |  |  |  |  |
Line of credit facility maximum increase to aggregate commitments | $ 1,700,000,000.0 |  |  |  |  | $ 1,525,000,000.0 | $ 1,700,000,000.0 | $ 2,000,000,000.0
Line of credit facility, maximum borrowing capacity | $ 1,525,000,000.0 |  |  |  |  |  |  | $ 1,500,000,000.0
Debt, weighted average interest rate |  | 1.90% | 1.80% |  |  |  |  |
Revolving credit facility | Minimum |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Loan term |  | 1 month |  |  |  |  |  |
Revolving credit facility | Maximum |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Loan term |  | 6 months |  |  |  |  |  |
2019 Notes |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Senior unsecured debt principal amount |  | $ 400,000,000.0 |  |  |  |  |  |
Senior unsecured notes stated interest rate |  |  |  |  | 7.25% |  |  |
2021 Notes |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Senior unsecured debt principal amount |  |  |  |  | $ 400,000,000.0 |  |  |
Senior unsecured notes stated interest rate |  |  |  |  | 6.50% |  |  |
2023 Notes |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Senior unsecured debt principal amount |  |  |  |  | $ 400,000,000.0 |  |  |
Senior unsecured notes stated interest rate |  |  |  |  | 6.875% |  |  |
2022 Notes |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Senior unsecured debt principal amount |  |  |  | $ 1,000,000,000.0 |  |  |  |
Senior unsecured notes stated interest rate |  |  |  | 6.875% |  |  |  |
Net proceeds from issuance of notes |  |  |  | $ 983,600,000 |  |  |  |
Unsecured Senior Notes |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Net proceeds from issuance of notes |  |  |  |  | $ 1,175,800,000 |  |  |
Redemption percentage, maximum |  | 35.00% |  |  |  |  |  |
Percentage of minimum outstanding principal amount |  | 65.00% |  |  |  |  |  |
Event of default by payment default |  | $ 10,000,000.0 |  |  |  |  |  |
Event of default by final judgments |  | 10,000,000.0 |  |  |  |  |  |
Consent Notes | Unsecured debt | Line of credit |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Current borrowing base |  | $ 1,525,000,000.0 |  |  |  |  |  |
Amended credit facility |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Commitment fee of borrowing base capacity not utilized, percentage |  | 0.375% |  |  |  |  |  |
Long-term line of credit |  | $ 138,000,000 |  |  |  |  |  |
Outstanding letters of credit |  | 5,200,000 |  |  |  |  |  |
Letter of credit unused borrowing base capacity |  | 1,381,800,000 |  |  |  |  |  |
Amended credit facility | Other current assets |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Deferred financing costs |  | $ 7,500,000 |  |  |  |  |  |
Amended credit facility | Current ratio |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Minimum current ratio |  | 1.0 |  |  |  |  |  |
Amended credit facility | Minimum | EBITDAX |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Minimum debt to EBITDAX ratio |  | 2.5 |  |  |  |  |  |

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