Accumulated Other Comprehensive Income/(Loss) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013	Jun. 30, 2012
Balance at beginning of period	$ 73	$ 176	$ 55
Other comprehensive income/(loss) before reclassifications	(61)	(165)
Amounts reclassified from accumulated other comprehensive income/(loss)	1	2
Other comprehensive income/(loss)	(60)	(163)
Balance at end of period	13	13	55
Foreign currency translation
Balance at beginning of period	80	184	61
Other comprehensive income/(loss) before reclassifications	(63)	(167)
Amounts reclassified from accumulated other comprehensive income/(loss)	0	0
Other comprehensive income/(loss)	(63)	(167)
Balance at end of period	17	17	61
Derivative financial instruments
Balance at beginning of period	(7)	(8)	(6)
Other comprehensive income/(loss) before reclassifications	2	2
Amounts reclassified from accumulated other comprehensive income/(loss)	1	2
Other comprehensive income/(loss)	3	4
Balance at end of period	$ (4)	$ (4)	$ (6)