Interest Expense (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Interest Income (Expense), Net [Abstract]
Interest expense	$ 158	$ 125	$ 480	$ 379
Interest income	(5)	(3)	(11)	(5)
Interest expense, net	$ 153	$ 122	$ 469	$ 374