Summary of Subsequent Additional Commodity Derivative Contracts (Detail) (Subsequent additional commodity derivative contracts)
Dec. 31, 2013
bbl
2015 Swap Oil | Oil (NYMEX WTI) | January 1, 2015 - June 30, 2015
 
Derivative [Line Items]  
Bbl per Day 1,000
Weighted Average Swap Price Per Bbl 90.31
2015 Swap Oil | Oil (NYMEX WTI) | 2015
 
Derivative [Line Items]  
Bbl per Day 3,000
Weighted Average Swap Price Per Bbl 89.05
Two Way | 2015 Collar | Oil (NYMEX WTI) | 2015
 
Derivative [Line Items]  
Bbl per Day 1,000
Weighted Average Floor Price per Bbl 84.17
Weighted Average Ceiling Price Per Bbl 92.10
Three Way | 2015 Collar | Gas (NYMEX HH) | January 1, 2015 - March 31, 2015
 
Derivative [Line Items]  
Bbl per Day 5,000
Weighted Average Short Put Price Per MMBtu 3.75
Weighted Average Floor Price per Bbl 4.50
Weighted Average Ceiling Price Per Bbl 5.55