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Shareholders' Equity (Details) (USD $) | 1 Months Ended | 3 Months Ended | 24 Months Ended
--- | --- | --- | ---
Apr. 30, 2012 | Mar. 31, 2014 | Mar. 31, 2013 | Mar. 31, 2014
Common Stock Programs |  |  |  |  |  |
Total cost of shares purchased |  | $ 600,000,000 |  |  |  |
Weighted average shares outstanding |  |  |  |  |  |
Shares for basic earnings per share (in shares) |  | 303,500,000 | [1] | 316,400,000 | [1] |
Common stock equivalents (in shares) |  | 3,700,000 |  | 3,600,000 |  |
Shares for diluted earnings per share (in shares) |  | 307,200,000 |  | 320,000,000 |  |
Number of participating securities (in shares) |  | 3,400,000 |  | 4,200,000 |  |
Number of shares excluded from the calculation of diluted earnings per share |  | 0 |  | 200,000 |  |
2012 - Share Repurchase Program [Member] |  |  |  |  |  |
Common Stock Programs |  |  |  |  |  |
Share repurchase authorization limit | 5,000,000,000 |  |  |  |  |
Shares purchased (in shares) |  | 7,200,000 |  | 5,000,000 |  | 43,500,000
Average price per share of stock repurchased |  | $ 83.45 |  | $ 59.82 |  |
Total cost of shares purchased |  | 600,000,000 |  | 300,000,000 |  | 2,700,000,000
Share repurchase, remaining authorization limit |  | $ 2,300,000,000 |  |  |  |
[1] | Includes 3.4 million and 4.2 million of participating securities for the three months ended March 31, 2014 and 2013, respectively

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