Derivative Financial Instruments (Effect Of Derivative Financial Instruments) (Details) (USD $) In Thousands	3 Months Ended				9 Months Ended
	Sep. 30, 2011		Sep. 30, 2010		Sep. 30, 2011		Sep. 30, 2010
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative financial instruments	$ 84,284		$ 56,209		$ 130,978		$ 156,020
Gain (Loss) On Derivative Financial Instruments [Member] | Commodity Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative financial instruments	84,284	[1]	56,209	[1]	130,978	[1]	156,065	[1]
Interest (Expense) Income [Member] | Interest Rate Swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative financial instruments	0	[2]	0	[2]	0	[2]	(45)	[2]
Interest Rate Swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net cash receipts and payments on derivatives settlement			0				(2,063)
Debt instrument maturity date					Feb. 14, 2010
Commodity Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net cash receipts and payments on derivatives settlement	$ 32,938		$ 43,075		$ 83,090		$ 166,660

[1] Included in these amounts are net cash receipts of $32,938 and $83,090 for the three and nine months ended September 30, 2011, respectively, and net cash receipts of $43,075 and $166,660 for the three and nine months ended September 30, 2010, respectively.

[2] Included in these amounts are net cash payments of $0 and $2,063 for the three and nine months ended September 30, 2010. Our interest rate swaps expired on February 14, 2010 and we have not entered into any new interest rate swap agreements as of September 30, 2011.