Financial Instruments And Risk Management (Effect Of Derivative Instruments On Statements Of Operations) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Amount of Gain (Loss) Recognized in OCI on Derivative	$ (13)	[1]	$ 48	[1]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	1	[1]	26	[1]
Amount of Gain (Loss) Recognized in Income, Ineffectiveness	$ 7	[2]	$ 3	[2]

[1] Effective portion of gain (loss

[2] Ineffective portion of gain (loss