Interest Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Interest Income (Expense), Net [Abstract]
Interest expense	$ 171	$ 161	$ 309	$ 322
Interest income	(5)	(3)	(9)	(6)
Interest expense, net	$ 166	$ 158	$ 300	$ 316