Income Taxes (Unrecognized Income Tax Benefits) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Tax Expense (Benefit) [Abstract]
Balance at January 1	$ 558	$ 568	$ 570
Gross increases for tax positions of prior years	30	17	67
Gross decreases for tax positions of prior years	(104)	(60)	(89)
Gross increases for tax positions of the current year	52	55	54
Settlements	(100)	(15)	(36)
Lapse of statute of limitations	(3)	(4)	0
Currency	2	(3)	2
Balance at December 31	$ 435	$ 558	$ 568