Fair Value Measurements (Details Textual) (USD $)	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 12,700,000,000	$ 12,800,000,000
Maturity period of bank time deposits, minimum, classified as time deposits (in days)	90 days
Time deposits	0	8,000,000
Time deposits, fair value	0	8,000,000
Restricted cash	1,100,000,000	1,500,000,000
Long-term debt, net carrying value	22,700,000,000	16,500,000,000
Level 1 [Member] | Corporate Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of debt	22,000,000,000
Level 2 [Member] | Other Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of debt	700,000,000
Carrying Value of Long-term Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, net carrying value	$ 22,000,000,000	$ 16,000,000,000
Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Maturity period of primarily bank time deposits, maximum, classified as cash equivalents and money market funds (in days)	90 days