Accumulated Other Comprehensive Loss (Schedule Of The Components Of Other Comprehensive Loss) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended							3 Months Ended
	Jun. 30, 2012	Mar. 31, 2012	Jun. 30, 2012 Commodity Derivatives [Member]	Mar. 31, 2012 Commodity Derivatives [Member]	Jun. 30, 2012 Treasury Lock [Member]	Mar. 31, 2012 Treasury Lock [Member]	Dec. 31, 2011 Treasury Lock [Member]	Jun. 30, 2012 Pension And Other Postretirement Benefit Plans [Member]	Dec. 31, 2011 Pension And Other Postretirement Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ (55)	$ (63)	$ (21)	$ (29)	$ (10)	$ (10)	$ (10)	$ (24)	$ (24)
Change in period	4	8	6	8				(2)
Ending Balance	$ (51)	$ (55)	$ (15)	$ (21)	$ (10)	$ (10)	$ (10)	$ (26)	$ (24)