XML 47 R53.htm IDEA: XBRL DOCUMENT v2.4.0.8
Financial Instruments - Effect of Derivative Instruments on Consolidated Statements of Operations (Detail) (Derivatives Not Designated as Cash-Flow Hedging Instruments [Member], USD $)
In Thousands, unless otherwise specified
 12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Derivatives not designated as cash-flow hedge instruments:    
Amount of gain/loss recognized in income $ (1,971) $ 3,985
Unrealized Gain (Loss) on Derivative Instruments, Net [Member] | Natural Gas Commodity Contracts [Member]
    
Derivatives not designated as cash-flow hedge instruments:    
Amount of gain/loss recognized in income (1,309) 1,040
Unrealized Gain (Loss) on Derivative Instruments, Net [Member] | Crude Oil Commodity Contracts [Member]
    
Derivatives not designated as cash-flow hedge instruments:    
Amount of gain/loss recognized in income 660 2,443
Realized Gain (Loss) on Derivative Instruments, Net [Member] | Natural Gas Commodity Contracts [Member]
    
Derivatives not designated as cash-flow hedge instruments:    
Amount of gain/loss recognized in income 796   
Realized Gain (Loss) on Derivative Instruments, Net [Member] | Crude Oil Commodity Contracts [Member]
    
Derivatives not designated as cash-flow hedge instruments:    
Amount of gain/loss recognized in income $ (2,118) $ 502