Share Repurchase Programs (Details) (USD $) In Millions	6 Months Ended	1 Months Ended								1 Months Ended				1 Months Ended	6 Months Ended
	Jun. 30, 2011	Oct. 31, 2008 Share Repurchase Program July 2008 [Member]	Jul. 31, 2008 Share Repurchase Program July 2008 [Member]	Jul. 31, 2009 Share Repurchase Program May 2009 Member	May 31, 2009 Share Repurchase Program May 2009 Member	Jan. 31, 2010 Share Repurchase Program July 2009 [Member]	Jul. 31, 2009 Share Repurchase Program July 2009 [Member]	Jan. 19, 2010 Share Repurchase Program July 2009 [Member]	Jul. 27, 2009 Share Repurchase Program July 2009 [Member]	May 31, 2010 Share Repurchase Program Feb 2010 [Member]	Feb. 28, 2010 Share Repurchase Program Feb 2010 [Member]	May 26, 2010 Share Repurchase Program Feb 2010 [Member]	Feb. 25, 2010 Share Repurchase Program Feb 2010 [Member]	Aug. 31, 2010 Share Repurchase Program Aug 2010 [Member]	Jun. 30, 2011 Share Repurchase Program Aug 2010 [Member]	May 31, 2011 Share Repurchase Program Aug 2010 [Member]	May 19, 2011 Share Repurchase Program Aug 2010 [Member]	Aug. 20, 2010 Share Repurchase Program Aug 2010 [Member]
Share Repurchase Program
Share repurchase authorization date			July 2008		May 2009		July 2009				February 2010			August 2010
Amount Authorized	$ 3,050		$ 400		$ 250			$ 750	$ 750			$ 250	$ 250		$ 241	$ 1,400	$ 1,400	$ 1,000
Completed		October 2008		July 2009		January 2010				May 2010
Number of Shares Repurchased	35.4	5.9		3.7		9.7				3.3					12.8