Derivatives (Amount Of Gain Or (Loss) Recognized In Accumulated OCI On Derivative) (Details) (Commodity Derivatives [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Commodity Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain Recognized in Accumulated OCI on Derivative (Effective Portion)	$ (3,838)	[1]	$ 13,503	[1]

[1] Net of taxes.