Retirement-Related Benefit Plans' Impact on Income Before Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended
	Aug. 31, 2018	Aug. 31, 2017
Pension Benefits | Domestic
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 9,382	$ 9,465
Interest cost	5,497	4,379
Expected return on plan assets	(8,467)	(8,086)
Prior service cost (credit)	29	29
Net actuarial losses recognized	3,272	3,618
Net Periodic Benefit (Credit) Cost	9,713	9,405
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
Interest cost	1,399	1,145
Expected return on plan assets	(2,051)	(1,978)
Prior service cost (credit)	(8)	(6)
Net actuarial losses recognized	319	419
Net Periodic Benefit (Credit) Cost	878	755
Postretirement Benefits | Domestic
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Interest cost	48	43
Prior service cost (credit)	(55)	(55)
Net actuarial losses recognized	(6)	6
Net Periodic Benefit (Credit) Cost	(13)	(6)
Postretirement Benefits | Non-U.S. Plans
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	392	311
Interest cost	291	224
Net actuarial losses recognized	115	79
Net Periodic Benefit (Credit) Cost	$ 798	$ 614