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Derivative Instruments And Hedging Activities (Narrative) (Details) (USD $)
6 Months Ended
Jun. 30, 2012
Jun. 30, 2011
Derivative Instruments and Hedges, Assets [Abstract]    
Ineffective portion of the change in fair value of the derivatives $ 0 $ 0
Fair value of derivatives in a net liability position 7,500,000  
Aggregate termination value to settle obligations $ 7,500,000