Derivative Activities (Gains (Losses) Of Derivative Contacts By Statement Of Operations Location) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative instrument	$ (48,619)		$ (52,633)		$ (14,414)		$ 41,909
Commodity Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative instrument	(45,377)	[1]	(49,461)	[1]	(11,860)	[1]	52,001	[1]
Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative instrument	$ (3,242)	[2]	$ (3,172)	[2]	$ (2,554)	[2]	$ (10,092)	[2]

[1] Gain (loss) on commodity derivative contracts is located in other income (expense) in the consolidated statements of operations.

[2] Gain (loss) on interest rate derivatives contracts is recorded as part of interest expense and is located in other income (expense) in the consolidated statements of operations.