v2.4.0.6
Derivatives - Additional Information (Detail)
Dec. 31, 2012
bbl
Crude Oil February 2013 December 2013 [Member] | Collar [Member]
 
Derivative [Line Items]  
Volume transacted in commodity derivatives position 1,200
Midland Cushing March 2013 December 2013 [Member] | Swap [Member]
 
Derivative [Line Items]  
Volume transacted in commodity derivatives position 2,300
Contract price in commodity derivatives position 1.10
Minimum [Member] | Crude Oil February 2013 December 2013 [Member] | Collar [Member]
 
Derivative [Line Items]  
Contract price in commodity derivatives position 90.35
Maximum [Member] | Crude Oil February 2013 December 2013 [Member] | Collar [Member]
 
Derivative [Line Items]  
Contract price in commodity derivatives position 100.35