Income Tax (Summary Of Unrecognized Tax Benefits) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income Tax [Abstract]
Balance at the beginning of the year	$ 93	$ 86	$ 118
Additions based on tax positions related to the current year	76	5
Additions based on tax positions of prior years	4	67	3
Reductions for tax positions of prior years	(43)	(4)	(21)
Settlements		(61)	(14)
Balance at the end of the year	$ 130	$ 93	$ 86