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Changes in Estimated Reserves (Parenthetical) (Detail)
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12 Months Ended | 12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
|
Dec. 31, 2013
Aneth Properties
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Dec. 31, 2012
Aneth Properties
|
Dec. 31, 2011
Aneth Properties
|
Dec. 31, 2013
Permian And Wyoming Properties
|
Dec. 31, 2013
Proved undeveloped reserves
Boe
|
Dec. 31, 2013
Henry Hub
|
Dec. 31, 2012
Henry Hub
|
Dec. 31, 2011
Henry Hub
|
Dec. 31, 2013
Future classification
Aneth Unit Phase 4 CO2 injection
Proved undeveloped reserves
Boe
|
Dec. 31, 2013
Future classification
McElmo Unit DCIIC CO2 injection
Proved undeveloped reserves
Boe
|
Dec. 31, 2013
Future classification
Aneth Field membrane plant
Proved undeveloped reserves
Boe
|
|
| Reserve Quantities [Line Items] | |||||||||||
| Oil price per Bbl | 96.94 | 94.71 | 96.19 | 93.42 | |||||||
| Spot market gas price per MMBtu | 3.67 | 2.76 | 4.12 | ||||||||
| Reduction of estimated proved undeveloped reserves | (25,000,000) | 8,000,000 | 8,000,000 | 7,000,000 | |||||||
| Expected period to convert undeveloped reserves to developed reserves | 5 years | ||||||||||
| Conversion of proved undeveloped reserves to proved developed reserves | 3,000,000 | ||||||||||