Interest Expense (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Interest Income (Expense), Net [Abstract]
Interest expense	$ 161	$ 127	$ 322	$ 254
Interest income	(3)	(1)	(6)	(2)
Interest expense, net	$ 158	$ 126	$ 316	$ 252