Summary of Option and Share-Based Payment Activity (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
May 31, 2018	May 31, 2017	May 31, 2016
Stock Options And Stock Appreciation Rights
Weighted Average Exercise Price
Beginning balance	$ 38.77
Options granted	55.19
Options exercised	23.65
Ending balance	43.36	$ 38.77
Exercisable at May 31, 2018	$ 37.74
Number of Shares Under Option
Beginning balance	3,055
Options granted	540
Options exercised	(388)
Ending balance	3,207	3,055
Exercisable at May 31, 2018	1,865
SARs
Number of Shares Under Option
Weighted-average grant-date fair value per SAR	$ 12.90	$ 10.90	$ 10.73
Intrinsic value of options exercised	$ 11,100	$ 26,500	$ 22,300
Tax benefit from options exercised	3,400	9,700	8,100
Fair value of SARS vested	$ 6,500	$ 4,600	$ 4,000

Amount of tax benefit from exercise of stock options granted under share-based compensation arrangement.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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Net number of share options (or share units) granted during the period.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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Number of share options (or share units) exercised during the current period.

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