Retirement-Related Benefit Plans' Impact on Income Before Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Nov. 30, 2018	Nov. 30, 2017	Nov. 30, 2018	Nov. 30, 2017
Pension Benefits | Domestic
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 9,382	$ 9,465	$ 18,764	$ 18,930
Interest cost	5,497	4,379	10,994	8,758
Expected return on plan assets	(8,467)	(8,086)	(16,934)	(16,172)
Prior service cost (credit)	29	29	58	58
Net actuarial (gains) losses recognized	3,272	3,618	6,544	7,236
Net Periodic Benefit (Credit) Cost	9,713	9,405	19,426	18,810
Pension Benefits | Non-U.S. Plans
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	1,219	1,175	2,438	2,350
Interest cost	1,399	1,145	2,798	2,290
Expected return on plan assets	(2,051)	(1,978)	(4,102)	(3,956)
Prior service cost (credit)	(8)	(6)	(16)	(12)
Net actuarial (gains) losses recognized	319	419	638	838
Net Periodic Benefit (Credit) Cost	878	755	1,756	1,510
Postretirement Benefits | Domestic
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Interest cost	48	43	96	86
Prior service cost (credit)	(55)	(55)	(110)	(110)
Net actuarial (gains) losses recognized	(6)	6	(12)	12
Net Periodic Benefit (Credit) Cost	(13)	(6)	(26)	(12)
Postretirement Benefits | Non-U.S. Plans
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	392	311	784	622
Interest cost	291	224	582	448
Net actuarial (gains) losses recognized	115	79	230	158
Net Periodic Benefit (Credit) Cost	$ 798	$ 614	$ 1,596	$ 1,228