Derivative Financial Instruments (Net Derivative Gains (Losses) Included In OCI And The Amount Reclassified Into Earnings) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in OCI	$ 33	$ 87
Amount of gain (loss) reclassified from AOCI into income (loss)	(28)	(11)
Commodities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in OCI	39	127
Amount of gain (loss) reclassified from AOCI into income (loss)	48	94
Foreign Exchange [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in OCI	(1)	4
Amount of gain (loss) reclassified from AOCI into income (loss)	10	2
Interest Rate Swaps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in OCI	(5)	(44)
Amount of gain (loss) reclassified from AOCI into income (loss)	$ (86)	$ (107)