Derivatives And Risk Management (Summary Of Before Tax Effect Of Fair Value Hedges Not Designated For Hedge Accounting) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Basis Swaps [Member]
Derivative [Line Items]
Derivative Instruments, Unrealized Gain (Loss) Recognized in Earnings	$ (10,184)		$ (2,950)
Derivative Instruments, Realized Gain (Loss) Recognized in Earnings	(14,270)	[1]	1,007	[1]
Fixed Price Call Options [Member]
Derivative [Line Items]
Derivative Instruments, Unrealized Gain (Loss) Recognized in Earnings	(26,913)		(57,082)
Fixed Price Swaps [Member]
Derivative [Line Items]
Derivative Instruments, Unrealized Gain (Loss) Recognized in Earnings	(22,585)		29,232
Derivative Instruments, Realized Gain (Loss) Recognized in Earnings	(23,453)	[1]
Interest Rate Swaps [Member]
Derivative [Line Items]
Derivative Instruments, Unrealized Gain (Loss) Recognized in Earnings	(2,202)
Derivative Instruments, Realized Gain (Loss) Recognized in Earnings	$ (113)	[1]

[1] The Company calculates gain (loss) on derivatives, settled, as the summation of gains and losses on positions that have settled within the period reported.