Property and Equipment, Net (Details Textual) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Property and Equipment Net (Textual) [Abstract]
Net Capital lease assets	$ 94	$ 64
Property and equipment additions	155	100
Depreciation expenses	145	139	121
Interest on capital projects capitalized	$ 3	$ 2