Debt - Key Components of Long-term Debt (Details) (USD $)	9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Issued at Discount to Par	1.00%
Carrying Value	$ 5,494,000,000	$ 5,494,000,000
Long-term Notes $2.5B
Debt Instrument [Line Items]
Debt, face amount	2,500,000,000
Stated interest rate	1.875%
Issued at Discount to Par	99.943%
Carrying Value	2,499,000,000
Long-term Notes $2.0B
Debt Instrument [Line Items]
Debt, face amount	2,000,000,000
Stated interest rate	2.65%
Issued at Discount to Par	99.76%
Carrying Value	1,996,000,000
Long-term Notes $1.0B
Debt Instrument [Line Items]
Debt, face amount	1,000,000,000
Stated interest rate	3.375%
Issued at Discount to Par	99.925%
Carrying Value	999,000,000
Long-term Notes $5.5B
Debt Instrument [Line Items]
Carrying Value	$ 5,494,000,000