Equity (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Sep. 30, 2011		Jun. 30, 2013		Jun. 30, 2012
Share repurchases
Total number of shares purchased					8.6	[1]	0.9	[1]
Total cash utilized	$ 0		$ 0		$ 500		$ 0
2011 Repurchase Program [Member]
Share repurchases
Total number of shares purchased	1.4	[1]	0.1	[1]

[1] include shares received as part of our accelerated share repurchase agreements described in more detail below.