Derivative Financial Instruments (Effect Of Derivative Financial Instruments) (Details) (Gain On Derivative Financial Instruments [Member], Commodity Contracts [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011
Gain On Derivative Financial Instruments [Member] | Commodity Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain on derivative financial instruments	$ 53,865	[1]	$ 3,421	[1]
Net cash receipts	$ 50,145		$ 26,935

[1] Included in these amounts are net cash receipts of $50,145 and $26,935 for the three months ended March 31, 2012 and 2011, respectively.