Financial Risk Management Activities (Schedule Of Reconciliation For Derivative Activity Included In Accumulated Other Comprehensive Loss) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Jun. 30, 2014	Sep. 30, 2014	Sep. 30, 2013
Gain (Loss) in AOCI	$ (13)	$ 28		$ 17	$ 54
(Gain) Loss into Income	(13)	(4)		(21)	(4)
Cash Flow Hedges [Member]
Pre-Tax Balance at Beginning of Period	1		(4)	(4)
Gain (Loss) in AOCI	3		(7)
(Gain) Loss into Income	(1)	(3)	12	11	(10)
Pre-Tax Balance at End of Period	3		1	3
After-Tax Balance at Beginning of Period	1		(2)	(2)
Gain (Loss) in AOCI	2	1	(4)	(2)	1
(Gain) Loss into Income	(1)	(2)	7	6	(6)
After-Tax Balance at End of Period	$ 2		$ 1	$ 2