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Supplemental Information on Oil and Natural Gas Producing Activities - Additional Information (Details) (USD $)
In Thousands, unless otherwise specified
 12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Reserve Quantities [Line Items]      
Percentage of proved reserves estimated by the Company 13.90%    
Standardized measure of discounted future net cash flows $ 4,017,611 [1] $ 5,840,368 [1] $ 5,216,337 [1]
Oil Reserves
      
Reserve Quantities [Line Items]      
Change in proved reserves (in MBbls for Oil/MMcf for Natural Gas)   67,900 37,600
Revisions of previous estimates (in MBbls for Oil and NGLs/MMcf for Natural Gas) (13,969) (37,394) (6,159)
Extensions and discoveries (in MBbls for Oil and NGLs/MMcf for Natural Gas) 40,570 89,656 52,406
Proved developed and undeveloped reserves, production (in MBbls for Oil/MMcf for Natural Gas) (14,279) (15,868) (9,992)
Natural Gas Reserves
      
Reserve Quantities [Line Items]      
Change in proved reserves (in MBbls for Oil/MMcf for Natural Gas)   60,500 68,600
Revisions of previous estimates (in MBbls for Oil and NGLs/MMcf for Natural Gas) (53,432) [2] (538,214) [2] (164,845) [2]
Extensions and discoveries (in MBbls for Oil and NGLs/MMcf for Natural Gas) 359,918 [2] 489,302 [2] 299,848 [2]
Proved developed and undeveloped reserves, production (in MBbls for Oil/MMcf for Natural Gas) (103,233) [2] (93,549) [2] (69,306) [2]
Natural Gas Liquids
      
Reserve Quantities [Line Items]      
Change in proved reserves (in MBbls for Oil/MMcf for Natural Gas)   40,900  
Revisions of previous estimates (in MBbls for Oil and NGLs/MMcf for Natural Gas) 3,717 15,098 (3,119)
Extensions and discoveries (in MBbls for Oil and NGLs/MMcf for Natural Gas) 18,686 27,259 3,171
Proved developed and undeveloped reserves, production (in MBbls for Oil/MMcf for Natural Gas) (2,291) (2,094) (1,838)
Permian properties and east Texas properties
      
Reserve Quantities [Line Items]      
Proved reserves, sales of minerals in place (in MMBoe)     122.7
Tertiary
      
Reserve Quantities [Line Items]      
Proved reserves, sales of minerals in place (in MMBoe)   23.6  
Permian Properties
      
Reserve Quantities [Line Items]      
Proved reserves (in MMBoe) 198.9    
Proved developed reserves as a percentage of total proved reserves 55.00%    
Standardized measure of discounted future net cash flows $ 2,500,000    
Mid-Continent and Permian Basin | Oil Reserves
      
Reserve Quantities [Line Items]      
Revisions of previous estimates (in MBbls for Oil and NGLs/MMcf for Natural Gas)   (22,300)  
Extensions and discoveries (in MBbls for Oil and NGLs/MMcf for Natural Gas)     52,406
Mid-Continent and Permian Basin | Natural Gas Reserves
      
Reserve Quantities [Line Items]      
Extensions and discoveries (in MBbls for Oil and NGLs/MMcf for Natural Gas)   489,302 [2] 299,848 [2]
Mid-Continent
      
Reserve Quantities [Line Items]      
Extensions and discoveries (in MMBoe) 119.2    
[1] Includes approximately $781.6 million, $952.7 million and $932.8 million attributable to noncontrolling interests at December 31, 2013, 2012 and 2011 respectively.
[2] Natural gas reserves are computed at 14.65 pounds per square inch absolute and 60 degrees Fahrenheit.