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Future Net Cash Flows Relating to Proved Oil and Gas Reserves (Detail) (USD $)
In Thousands, unless otherwise specified |
12 Months Ended | |||
|---|---|---|---|---|
|
Dec. 31, 2013
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Dec. 31, 2012
|
Dec. 31, 2011
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Dec. 31, 2010
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| Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves [Line Items] | ||||
| Future cash inflows | $ 4,647,000 | $ 5,983,000 | $ 5,190,000 | |
| Future production costs | (2,050,000) | (2,678,000) | (2,081,000) | |
| Future development costs | (547,000) | (832,000) | (648,000) | |
| Future income taxes | (398,000) | (645,000) | (733,000) | |
| Future net cash flows | 1,652,000 | 1,828,000 | 1,728,000 | |
| 10% annual discount for estimated timing of cash flows | (759,000) | (956,000) | (912,000) | |
| Standardized measure of discounted future net cash flows | $ 893,000 | $ 872,000 | $ 816,000 | $ 587,000 |