Derivatives And Risk Management (Summary Of Before Tax Effect Of Cash Flow Hedges On Consolidated Financial Statements) (Details) (Fixed Price Swaps [Member], USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income, Effective Portion	$ 80	$ 13	$ (2)	$ 51
Gas Sales [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated Other Comprehensive Income into Earnings, Effective Portion	18	93	(48)	218
Derivative Instruments, Gain (Loss) Recognized in Earnings, Ineffective Portion	$ 3	$ (1)	$ 1	$ (2)