Provision for Income Taxes (Reconciliation of Amounts of Unrecognized Tax Benefits) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Total Unrecognized Tax Benefits as of January 1	$ 805	$ 800	$ 693
Gross amounts of decreases in unrecognized tax benefits as a result of tax positions taken during the prior period	(28)	(94)	(82)
Gross amounts of increases in unrecognized tax benefits as a result of tax positions taken during the prior period	76	73	170
Gross amounts of increases in unrecognized tax benefits as a result of tax positions taken during the current period	92	78	79
Amount of decreases in unrecognized tax benefits relating to settlements with taxing authorities	(19)	(29)	(6)
Reduction to unrecognized tax benefits as a result of a lapse of the applicable statute of limitations	(6)	(10)	(32)
Exchange gain (loss)	(19)	(13)	(22)
Total Unrecognized Tax Benefits as of December 31	901	805	800
Total unrecognized tax benefits that, if recognized, would impact the effective tax rate	778	693	683
Total amount of interest and penalties recognized in the Consolidated Income Statements	16	4	7
Total amount of interest and penalties recognized in the Consolidated Balance Sheets	$ 122	$ 116	$ 113