Accumulated Other Comprehensive Income (loss) (Detail) - USD ($) $ in Thousands	12 Months Ended
	May 31, 2020	May 31, 2019	May 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 1,408,605	$ 1,633,538	$ 1,438,700
Deferred taxes	(23,403)	(19,068)	3,773
Ending Balance	1,264,663	1,408,605	1,633,538
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(370,495)	(300,013)	(308,415)
Other comprehensive income (loss)	(71,820)	(73,660)	10,989
Deferred taxes	1,583	3,178	(2,587)
Ending Balance	(440,732)	(370,495)	(300,013)
Pension And Other Postretirement Benefit Liability Adjustments, Net of Tax
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(211,645)	(157,495)	(166,724)
Other comprehensive income (loss)	(86,347)	(70,785)	11,375
Deferred taxes	20,275	16,635	(2,146)
Ending Balance	(277,717)	(211,645)	(157,495)
Unrealized Gain (Loss) On Derivatives, Net of Tax
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	4,379	(131)	16
Other comprehensive income (loss)	(6,315)	4,713	(359)
Deferred taxes	1,865	(203)	212
Ending Balance	(71)	4,379	(131)
Unrealized Gain (Loss) On Securities, Net of Tax
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	133	(1,409)	1,137
Reclassification adjustments for gains (losses) included in net income, net of taxes of $151, $591, $401 in 2020, 2019 and 2018		1,777	(1,244)
Other comprehensive income (loss)	1,210	307	(2,050)
Deferred taxes	(320)	(542)	748
Ending Balance	1,023	133	(1,409)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(577,628)	(459,048)	(473,986)
Reclassification adjustments for gains (losses) included in net income, net of taxes of $151, $591, $401 in 2020, 2019 and 2018		1,777	(1,244)
Other comprehensive income (loss)	(163,272)	(139,425)	19,955
Deferred taxes	23,403	19,068	(3,773)
Ending Balance	$ (717,497)	$ (577,628)	$ (459,048)