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Shareholders' Equity (Details) - USD ($) | 1 Months Ended | 3 Months Ended | 6 Months Ended | 63 Months Ended |  |  |
--- | --- | --- | --- | --- | --- | --- | ---
Jul. 31, 2017 | Jun. 30, 2017 | Jun. 30, 2016 | Jun. 30, 2017 | Jun. 30, 2016 | Jun. 30, 2017 | Feb. 28, 2017 | Nov. 30, 2014 | Apr. 30, 2012
Common Stock Programs |  |  |  |  |  |  |  |  |
Shares purchased (in shares) |  |  |  |  |  | 99,300,000 |  |  |
Total cost of shares purchased |  |  |  | $ 1,160,000,000 |  | $ 8,300,000,000 |  |  |
Treasury stock acquired, additional transaction costs |  | $ 5,100,000 |  | $ 5,800,000 |  |  |  |  |
Weighted average shares outstanding |  |  |  |  |  |  |  |  |
Shares for basic earnings per share (in shares) |  | 262,400,000 | 268,000,000 | 263,600,000 | 269,900,000 |  |  |  |
Dilutive effect of potentially issuable shares (in shares) |  | 0 | 1,800,000 | 2,100,000 | 1,800,000 |  |  |  |
Shares for diluted earnings per share (in shares) |  | 262,400,000 | 269,800,000 | 265,700,000 | 271,700,000 |  |  |  |
Number of shares excluded from the calculation of diluted earnings per share (in shares) |  | 1,900,000 | 0 | 200,000 | 300,000 |  |  |  |
Share Repurchase Program of 2014 |  |  |  |  |  |  |  |  |
Common Stock Programs |  |  |  |  |  |  |  |  |
Share repurchase authorization limit (up to) |  |  |  |  |  |  | $ 5,000,000,000.0 | $ 5,000,000,000.0 |
Share repurchase, remaining authorization limit (shares) |  | $ 6,700,000,000 |  | $ 6,700,000,000 |  | $ 6,700,000,000 |  |  |
2012 - Share Repurchase Program |  |  |  |  |  |  |  |  |
Common Stock Programs |  |  |  |  |  |  |  |  |
Share repurchase authorization limit (up to) |  |  |  |  |  |  |  |  | $ 5,000,000,000.0
Shares purchased (in shares) |  | 8,000,000 | 0 | 9,100,000 | 7,700,000 |  |  |  |
Average price per share of stock repurchased (in usd per share) |  | $ 128.54 |  | $ 126.85 | $ 97.92 |  |  |  |
Total cost of shares purchased |  | $ 1,000,000,000 |  | $ 1,200,000,000 | $ 750,000,000 |  |  |  |
Subsequent Event | 2012 - Share Repurchase Program |  |  |  |  |  |  |  |  |
Common Stock Programs |  |  |  |  |  |  |  |  |
Shares purchased (in shares) | 450,000 |  |  |  |  |  |  |  |
Average price per share of stock repurchased (in usd per share) | $ 133.24 |  |  |  |  |  |  |  |
Total cost of shares purchased | $ 60,000,000 |  |  |  |  |  |  |  |

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