Summary of Changes in Equity by Component and in Total (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Nov. 30, 2017	Nov. 30, 2016	Nov. 30, 2017	Nov. 30, 2016
Balance as of May 31, 2017			$ 1,073,929
Net earnings	$ 41,622	$ 49,867	89,696	$ 118,403
Other comprehensive income	(699)	$ (5,865)	17,054	$ (5,905)
Common shares issued, net of withholding tax			(3,996)
Common shares in NQ plans			886
Stock-based compensation			7,991
Purchases and retirement of common shares			(112,524)
Cash dividends declared			(26,337)
Dividends to noncontrolling interest			(3,916)
Balance as of November 30, 2017	1,042,783		1,042,783
Additional Paid-in Capital
Balance as of May 31, 2017			303,391
Common shares issued, net of withholding tax			(3,996)
Common shares in NQ plans			886
Stock-based compensation			7,991
Purchases and retirement of common shares			(11,480)
Balance as of November 30, 2017	296,792		296,792
Accumulated Other Comprehensive Loss, Net of Tax
Balance as of May 31, 2017			(27,775)
Other comprehensive income			16,695
Balance as of November 30, 2017	(11,080)		(11,080)
Retained Earnings
Balance as of May 31, 2017			676,019
Net earnings			84,937
Purchases and retirement of common shares			(101,044)
Cash dividends declared			(26,337)
Balance as of November 30, 2017	633,575		633,575
Parent
Balance as of May 31, 2017			951,635
Net earnings			84,937
Other comprehensive income			16,695
Common shares issued, net of withholding tax			(3,996)
Common shares in NQ plans			886
Stock-based compensation			7,991
Purchases and retirement of common shares			(112,524)
Cash dividends declared			(26,337)
Balance as of November 30, 2017	919,287		919,287
Noncontrolling Interest
Balance as of May 31, 2017			122,294
Net earnings			4,759
Other comprehensive income			359
Dividends to noncontrolling interest			(3,916)
Balance as of November 30, 2017	$ 123,496		$ 123,496