Earnings Per Share, Share Repurchases and Dividends on Common Stock (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	1 Months Ended						3 Months Ended		12 Months Ended			21 Months Ended	12 Months Ended				0 Months Ended	12 Months Ended						3 Months Ended	21 Months Ended	9 Months Ended
	Sep. 30, 2012	May 31, 2012	May 31, 2011	Apr. 30, 2011	May 31, 2010	May 31, 2009	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012	Dec. 31, 2012 December 19, 2007 Program - Total Authorization		Dec. 31, 2011 December 19, 2007 Program - Total Authorization	Dec. 31, 2010 December 19, 2007 Program - Total Authorization	Jun. 16, 2010 June 16, 2010 Program - Original Authorization	Dec. 31, 2012 June 16, 2010 Program - Original Authorization		Dec. 31, 2011 June 16, 2010 Program - Original Authorization		Dec. 31, 2010 June 16, 2010 Program - Original Authorization		Mar. 31, 2011 Private Letter Ruling Limitation [Member]	Dec. 31, 2012 Private Letter Ruling Limitation [Member]	Sep. 30, 2012 Maximum [Member]
Diluted Earnings Per Share (Amounts in Paragraphs)
Dilutive effect of stock options and other stock awards granted									4.8	4.8	4.2
Antidilutive stock options									1.8	2.8	2.8
Share Repurchases (Table Amounts)
Amount Authorized													$ 3,600,000,000				$ 2,000,000,000	$ 5,350,000,000	[1]
Total shares retired													60.2					65.1	[1]
Treasury Stock Acquired, Average Cost Per Share													$ 59.82	[2]				$ 59.42	[1],[2]
Shares repurchased									20.9	40.2	19.7		0		0	15.7		20.9	[1]	40.2	[1]	4.0	[1]
Increase authorized	2,000,000,000			4,000,000,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount																										1,000,000,000
Amount repurchased							487,000,000	649,000,000				3,900,000,000
Amount remaining under authorization for share repurchases							$ 1,500,000,000		$ 1,500,000,000			$ 1,500,000,000
Share Repurchases (Amounts in Paragraphs)
Share repurchase limit due to IRS action																								88
Period of share repurchase limit																								2 years
Stock Repurchased During Period, Shares							7.3	11.8																	61.0
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased																									27
Common Stock, Dividends, Per Share, Declared		$ 0.55	$ 0.50		$ 0.47	$ 0.43			$ 2.15	$ 1.97	$ 1.84

[1] On June 16, 2010, the company’s board of directors authorized a share repurchase program of up to $2.0 billion of the company’s common stock. Following this initial authorization, the board of directors increased the remaining repurchase authorization to $4.0 billion in April 2011. After further repurchases reduced the remaining authorization to less than $1 billion, the board of directors again increased the remaining authorization to $2.0 billion in September 2012. As of December 31, 2012, repurchases under the program totaled $3.9 billion, and $1.5 billion remained under this share repurchase authorization. The repurchase program will expire when we have used all authorized funds for repurchase.

[2] Includes commissions paid.