Computation of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended	6 Months Ended
Nov. 30, 2015	Nov. 30, 2014	Nov. 30, 2015	Nov. 30, 2014
Basic earnings per common share:
Net earnings allocable to common shares	$ 690	$ 662	$ 1,382	$ 1,315
Weighted-average common shares	279.0	283.0	281.0	284.0
Basic earnings per common share	$ 2.47	$ 2.34	$ 4.92	$ 4.63
Diluted earnings per common share:
Net earnings allocable to common shares	$ 690	$ 662	$ 1,382	$ 1,315
Weighted-average common shares	279.0	283.0	281.0	284.0
Dilutive effect of share-based awards	4.0	4.0	3.0	4.0
Weighted-average diluted shares	283.0	287.0	284.0	288.0
Diluted earnings per common share	$ 2.44	$ 2.31	$ 4.86	$ 4.57
Anti-dilutive options excluded from diluted earnings per common share	3.7	2.2	3.6	2.2

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.

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Net income after adjustments for dividends on preferred stock (declared in the period) and/or cumulative preferred stock (accumulated for the period).

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Net Income or Loss Available to Common Stockholders plus adjustments resulting from the assumption that dilutive convertible securities were converted, options or warrants were exercised, or that other shares were issued upon the satisfaction of certain conditions.

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The sum of dilutive potential common shares or units used in the calculation of the diluted per-share or per-unit computation.

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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

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