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Earnings per Common Share Earnings per Common Share - Narrative (Details) - $ / shares shares in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2018 | Sep. 30, 2017 | Sep. 30, 2018 | Sep. 30, 2017
Earnings Per Share [Abstract] |  |  |  |
Antidilutive stock options, exercise price exceeds market price (in shares) | 2.3 | 0.2 | 1.9 | 2.5
Antidilutive stock options, exercise price exceeds market price, exercise price range, low end of range (in dollars per share) | $ 84.93 | $ 78.35 | $ 84.93 | $ 74.03
Antidilutive stock options, exercise price exceeds market price, exercise price range, high end of range (in dollars per share) | $ 102.84 | $ 93.93 | $ 102.84 | $ 93.93

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- Definition The high end of the range of specified exercise prices for stock options with exercise prices exceeding the average market price of common shares during the period or for which the unrecognized compensation cost would have an anti-dilutive effect. + References No definition available. + Details
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- Definition The low end of the range of specified exercise prices for stock options with exercise prices exceeding the average market price of common shares during the period or for which the unrecognized compensation cost would have an anti-dilutive effect. + References No definition available. + Details
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- Definition Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 + Details
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- References No definition available. + Details
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