Shareholders' Equity (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	1 Months Ended	3 Months Ended		6 Months Ended		15 Months Ended
	Apr. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013
Common Stock Programs
Total cost of shares purchased				$ 525,000,000
Weighted average shares outstanding
Shares for basic earnings per share		313.7	332.0	315.0	332.2
Common stock equivalents (in shares)		3.4	3.6	3.6	3.9
Shares for diluted earnings per share		317.1	335.6	318.6	336.1
Number of participating securities (in shares)		4.0	4.8	4.1	4.8
Number of shares excluded from the calculation of diluted earnings per share		0	1.1	0.4	0.6
2012 - Share Repurchase Program [Member]
Common Stock Programs
Share repurchase authorization limit	5,000,000,000
Shares purchased (in shares)		3.5	5.3	8.5	7.4	28.0
Average price per share of stock repurchased		$ 64.53	$ 47.40	$ 61.75	$ 47.66
Total cost of shares purchased		225,000,000	250,000,000	525,000,000	350,000,000	1,500,000,000
Share repurchase, remaining authorization limit		$ 3,500,000,000