Earnings Per Share (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2011	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2011 December 19, 2007 Program - Total Authorization	Dec. 31, 2010 December 19, 2007 Program - Total Authorization	Dec. 31, 2009 December 19, 2007 Program - Total Authorization	Dec. 31, 2011 June 16, 2010 Program - Original Authorization	Dec. 31, 2010 June 16, 2010 Program - Original Authorization	Apr. 25, 2011 June 16, 2010 Program - Original Authorization
Share Repurchases (Table Amounts)
Amount Authorized					$ 3,600,000,000			$ 4,245,000,000	$ 2,000,000,000
Average price per share					$ 59.82			$ 57.42
Total shares retired					60.2			44.2
Shares repurchased		40.2	19.7	23.1		15.7	23.1	40.2	4.0
Share Repurchases (Amounts in Paragraphs)
Increase authorized								4,000,000,000
Amount remaining under authorization for share repurchases								1,700,000,000
Amount Repurchased										245,000,000
Shares to be repurchased as part of accelerated share repurchase agreement		15.6
Shares to be repurchased as part of accelerated share repurchase agreement initial price per share		$ 64.17
Amount to be repurchased as a part of accelerated share repurchase agreement		1,000,000,000
Cash refund in connection with share repurchase		$ 19,000,000
Final average purchase price per share under accelerated share repurchase agreement		$ 62.54
Share repurchase limit due to IRS action	88	48
Period of share repurchase limit	2 years	1 year 3 months
Percent of outstanding shares at the time of the separation		30.00%
Diluted Earnings Per Share (Amounts in Paragraphs)
Dilutive effect of stock options and other stock awards granted		4.8	4.2	4.1
Antidilutive stock options		2.8	2.8	8.1