Interest Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Interest Income (Expense), Net [Abstract]
Interest expense	$ 268	$ 158	$ 577	$ 480
Interest income	(7)	(5)	(15)	(11)
Interest expense, net	$ 261	$ 153	$ 562	$ 469