Derivatives (Effect Of Commodity Derivative Instruments In Statements Of Income) (Detail) (Commodity Derivatives [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss)	$ (168)	$ 73	$ 149
Sales And Other Operating Revenues [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss)	12	8	(34)
Other Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss)	0	0	1
Cost Of Revenues [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss)	$ (180)	$ 65	$ 182