Interest Expense (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Interest Income (Expense), Net [Abstract]
Interest expense	$ 127	$ 132	$ 254	$ 264
Interest income	(1)	0	(2)	(1)
Interest expense, net	$ 126	$ 132	$ 252	$ 263