XML 53 R41.htm IDEA: XBRL DOCUMENT v2.4.0.6
Financial Instruments (Details 3) (Derivatives not designated as cash-flow hedging instruments [Member], Cash Flow Hedging [Member], USD $)
In Thousands, unless otherwise specified
9 Months Ended
Sep. 30, 2012
Sep. 30, 2011
Derivatives not designated as cash-flow hedge instruments    
Amount of gain/loss recognized in income $ 2,828 $ 13,446
Unrealized gain 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   106
Unrealized gain 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 2,449 8,909
Realized gain 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   2,969
Realized gain 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 $ 379 $ 1,462