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Shareholders' Equity (Details) - USD ($) $ / shares in Units, $ in Millions | 3 Months Ended | 60 Months Ended |  |
--- | --- | --- | --- | ---
Mar. 31, 2017 | Mar. 31, 2016 | Mar. 31, 2017 | Feb. 28, 2017 | Apr. 30, 2012
Common Stock Programs |  |  |  |  |
Shares purchased (in shares) |  |  | 91,300,000 |  |
Total cost of shares purchased | $ 126.0 |  | $ 7,300.0 |  |
Treasury stock acquired, additional transaction costs | $ 0.6 |  |  |  |
Weighted average shares outstanding |  |  |  |  |
Shares for basic earnings per share (in shares) | 264,800,000 | 271,700,000 |  |  |
Dilutive effect of potentially issuable shares (in shares) | 2,200,000 | 2,000,000 |  |  |
Shares for diluted earnings per share (in shares) | 267,000,000 | 273,700,000 |  |  |
Number of shares excluded from the calculation of diluted earnings per share (in shares) | 0 | 500,000 |  |  |
Share Repurchase Program of 2014 |  |  |  |  |
Common Stock Programs |  |  |  |  |
Share repurchase authorization limit (up to) |  |  |  | $ 5,000.0 |
Share repurchase, remaining authorization limit (shares) | $ 7,700.0 |  | $ 7,700.0 |  |
2012 - Share Repurchase Program |  |  |  |  |
Common Stock Programs |  |  |  |  |
Share repurchase authorization limit (up to) |  |  |  |  | $ 5,000.0
Shares purchased (in shares) | 1,100,000 | 7,700,000 |  |  |
Average price per share of stock repurchased (in usd per share) | $ 114.46 | $ 97.92 |  |  |
Total cost of shares purchased | $ 125.0 | $ 750.0 |  |  |

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