Derivatives And Risk Management (Summary Of Before Tax Effect Of Fair Value Hedges Not Designated For Hedge Accounting) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013	Jun. 30, 2014		Jun. 30, 2013
Basis Swaps [Member]
Derivative [Line Items]
Derivative Instruments, Unrealized Gain (Loss) Recognized in Earnings	$ (3)		$ 10	$ (13)		$ 7
Derivative Instruments, Realized Gain (Loss) Recognized in Earnings	5	[1]		(10)	[1]	1	[1]
Fixed Price Call Options [Member]
Derivative [Line Items]
Derivative Instruments, Unrealized Gain (Loss) Recognized in Earnings	4		22	(23)		(35)
Fixed Price Swaps [Member]
Derivative [Line Items]
Derivative Instruments, Unrealized Gain (Loss) Recognized in Earnings	2		58	(21)		88
Derivative Instruments, Realized Gain (Loss) Recognized in Earnings	(13)	[1]		(36)	[1]
Interest Rate Swaps [Member]
Derivative [Line Items]
Derivative Instruments, Unrealized Gain (Loss) Recognized in Earnings	$ (3)		$ 3	$ (5)		$ 3

[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.