Derivative Instruments And Hedging Activities (Narrative) (Details) (USD $)	3 Months Ended	6 Months Ended
	Jun. 30, 2012 bbl	Jun. 30, 2012 bbl
Total volume of oil units	4,300,000	4,300,000
Total Volume Of Gas Units	11,600,000,000	11,600,000,000
Term loans payable	$ 200,000,000	$ 200,000,000
Gain (Loss) on Sale of Commodity Contracts	10,069,000	7,730,000
Oil And Natural Gas Commodity Contracts [Member]
Future amount to be re-classified to earnings		9,100,000
Interest Rate Contracts [Member]
Future amount to be re-classified to earnings		$ (200,000)