Repurchase of Common Stock (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended		6 Months Ended		1 Months Ended	3 Months Ended		6 Months Ended
	Jun. 30, 2007 June 2007 share repurchase program	Aug. 04, 2012 June 2007 share repurchase program	Jul. 30, 2011 June 2007 share repurchase program	Aug. 04, 2012 June 2007 share repurchase program	Jul. 30, 2011 June 2007 share repurchase program	Jun. 30, 2011 June 2011 share repurchase program	Aug. 04, 2012 June 2011 share repurchase program	Jul. 30, 2011 June 2011 share repurchase program	Aug. 04, 2012 June 2011 share repurchase program	Jul. 30, 2011 June 2011 share repurchase program
Repurchases of common stock
Share repurchase program, authorized amount	$ 5,500					$ 5,000
Common stock repurchased and retired (in shares)		0	9.2	0	20.1		6.3	4.6	10.9	4.6
Common stock repurchased and retired		0	286	0	611		122	139	237	139
Amount remained available for future repurchases									$ 3,989