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Earnings per Share - Summary of Buyback Activity by Program (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands | 12 Months Ended
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May 31, 2017 | May 31, 2016 | May 31, 2015
Equity, Class of Treasury Stock [Line Items] |  |  |
Purchase Price | $ 20,724 | $ 780,151 | $ 551,970
Share Repurchase Programs |  |  |
Equity, Class of Treasury Stock [Line Items] |  |  |
Shares | 39 | 8,727 | 6,851
Avg. Price per Share (in dollars per share) | $ 94.09 | $ 87.00 | $ 78.47
Purchase Price | $ 3,691 | $ 759,237 | $ 537,572
July 30, 2013 |  |  |
Equity, Class of Treasury Stock [Line Items] |  |  |
Shares | 0 | 0 | 3,981
Avg. Price per Share (in dollars per share) | $ 0.00 | $ 0.00 | $ 75.49
Purchase Price | $ 0 | $ 0 | $ 300,500
January 13, 2015 |  |  |
Equity, Class of Treasury Stock [Line Items] |  |  |
Shares | 0 | 3,078 | 2,870
Avg. Price per Share (in dollars per share) | $ 0.00 | $ 85.44 | $ 82.60
Purchase Price | $ 0 | $ 262,928 | $ 237,072
August 4, 2015 |  |  |
Equity, Class of Treasury Stock [Line Items] |  |  |
Shares | 39 | 5,649 | 0
Avg. Price per Share (in dollars per share) | $ 94.09 | $ 87.85 | $ 0.00
Purchase Price | $ 3,691 | $ 496,309 | $ 0
August 6, 2016 |  |  |
Equity, Class of Treasury Stock [Line Items] |  |  |
Shares | 0 | 0 | 0
Avg. Price per Share (in dollars per share) | $ 0.00 | $ 0.00 | $ 0.00
Purchase Price | $ 0 | $ 0 | $ 0

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- Definition Total cost of shares repurchased divided by the total number of shares repurchased. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6405813&loc=d3e23239-112655 + Details
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- Definition Number of shares that have been repurchased during the period and are being held in treasury. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21463-112644 + Details
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