Stock-Based Compensation - Summary of Stock Option 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
Outstanding, beginning of year	2,307	3,306	4,044
Granted	90	111	154
Exercised	(371)	(1,076)	(874)
Forfeited	(7)	(34)	(18)
Outstanding, end of year	2,019	2,307	3,306
Exercisable at end of year	1,800	2,067	3,059
Weighted Average Exercise Price
Outstanding, beginning of year	$ 20.99	$ 19.01	$ 18.25
Granted	47.76	42.30	30.92
Exercised	20.37	16.90	17.22
Forfeited	33.02	29.95	32.25
Outstanding, end of year	22.26	20.99	19.01
Exercisable at end of year	$ 20.03	$ 19.17	$ 17.85
Weighted Average Remaining Contractual Life (in years)
Outstanding	3 years 7 months 2 days	3 years 11 months 12 days	4 years 3 months 29 days
Exercisable	3 years 21 days	3 years 5 months 19 days	4 years 3 days
Aggregate intrinsic value
Outstanding	$ 51,858	$ 48,509	$ 61,178
Exercisable	$ 50,673	$ 47,488	$ 60,082

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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Balance Type:	na
Period Type:	instant

- Definition

The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.