Income Taxes (Reconciliation Of Beginning And Ending Unrecognized Tax Benefits) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Tax Disclosure [Abstract]
Balance at beginning of year	$ 381	$ 399	$ 601
Additions based on tax positions related to the current year	15	22	21
Additions for tax positions of prior years	170	71	30
Reductions for tax positions due to lapse of statutes of limitations	(16)	(39)	(58)
Reductions for tax positions of prior years	(102)	(67)	(164)
Settlements	(186)	(5)	(31)
Balance at end of year	$ 262	$ 381	$ 399