Fair Value Measurements (Details Textual) (USD $)	9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011
Fair Value Measurements (Textual) [Abstract]
Maturity period of primarily bank time deposits, maximum, classified as cash equivalents (in days)	90 days
Cash and cash equivalents	$ 21,300,000,000	$ 15,900,000,000
Maturity period of bank time deposits, minimum, classified as time deposits (in days)	90 days
Time deposits	8,000,000	4,000,000,000
Restricted cash	$ 1,300,000,000	$ 1,200,000,000