XML 64 R38.htm IDEA: XBRL DOCUMENT v2.4.0.6
Derivative Instruments (Realized And Unrealized Gains And Losses From Commodity Derivative Instruments) (Details) (USD $)
In Thousands, unless otherwise specified
3 Months Ended
Mar. 31, 2012
Mar. 31, 2011
Derivative Instruments [Abstract]    
Change in unrealized loss on derivative instruments $ (17,295) $ (31,154)
Realized loss on derivative instruments (1,291) (512)
Total net loss on derivative instruments $ (18,586) $ (31,666)