Property and Equipment, Net (Details Textual) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Property and Equipment Net (Textual) [Abstract]
Property and equipment additions			$ (61)	$ (55)
Depreciation expenses	36	34	108	101
Capital lease assets	56		56		64
Interest on capital projects capitalized	$ 1	$ 1	$ 2	$ 2