Shareholders' Equity (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	1 Months Ended	3 Months Ended				9 Months Ended				18 Months Ended
	Apr. 30, 2012	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013
Common Stock Programs
Total cost of shares purchased						$ 1,025,000,000
Weighted average shares outstanding
Shares for basic earnings per share		309.5	[1]	327.3	[1]	313.2	[1]	330.6	[1]
Common stock equivalents (in shares)		3.4		3.7		3.5		3.8
Shares for diluted earnings per share		312.9		331.0		316.7		334.4
Number of participating securities (in shares)		3.8		4.5		4.0		4.7
Number of shares excluded from the calculation of diluted earnings per share		0		0.1		0		0.1
2012 - Share Repurchase Program [Member]
Common Stock Programs
Share repurchase authorization limit	5,000,000,000
Shares purchased (in shares)		7.3		5.4		15.8		12.7		35.3
Average price per share of stock repurchased		$ 68.33		$ 51.37		$ 64.79		$ 49.22
Total cost of shares purchased		500,000,000		275,000,000		1,000,000,000		625,000,000		2,000,000,000
Share repurchase, remaining authorization limit		$ 3,000,000,000

[1] Includes 3.8 million and 4.5 million of participating securities for the three months ended September 30, 2013 and 2012, respectively, and 4.0 million and 4.7 million of participating securities for the nine months ended September 30, 2013 and 2012, respectively.