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Stock and Stock-Based Incentive Plans Stock and Stock-Based Incentive Plans (Narrative) (Details) - USD ($) $ in Millions | 3 Months Ended |
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Aug. 31, 2016 | May 31, 2016 | Aug. 31, 2017
Stock and Stock-Based Incentive Plans |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Plan Modification, Incremental Compensation Cost | $ 10.9 | $ 3.5 |
Share Repurchase Program |  |  |
Stock and Stock-Based Incentive Plans |  |  |
Stock Repurchase Program, Authorized Amount |  |  | $ 4,550.0
Available for repurchase, as of end of period | $ 1,890.2 |  | $ 1,251.8

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- Definition An excess of the fair value of the modified award over the fair value of the award immediately before the modification. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(2)(iii) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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