Repurchase of Common Stock (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended		1 Months Ended	3 Months Ended
	Jun. 30, 2007 June 2007 share repurchase program	May 05, 2012 June 2007 share repurchase program	Apr. 30, 2011 June 2007 share repurchase program	Jun. 30, 2011 June 2011 share repurchase program	May 05, 2012 June 2011 share repurchase program	Apr. 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	10.9		4.6	0
Common stock repurchased and retired		0	325		115	0
Amount remained available for future repurchases					$ 4,111