Retirement-Related Benefit Plans' Impact on Income Before Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Nov. 30, 2016	Nov. 30, 2015	Nov. 30, 2016	Nov. 30, 2015
Pension Benefits, U.S. Plans
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 9,401	$ 8,202	$ 18,802	$ 16,404
Interest cost	4,331	4,499	8,662	8,998
Expected return on plan assets	(6,252)	(6,437)	(12,504)	(12,874)
Amortization of Prior service cost (credit)	54	58	108	116
Amortization of Net actuarial (gains) losses recognized	5,540	4,190	11,080	8,380
Net Periodic Benefit Cost	13,074	10,512	26,148	21,024
Pension Benefits, Non-U.S. Plans
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	1,127	1,067	2,254	2,134
Interest cost	1,224	1,323	2,448	2,646
Expected return on plan assets	(1,886)	(1,983)	(3,772)	(3,966)
Amortization of Net actuarial (gains) losses recognized	573	457	1,146	914
Settlement		91		91
Net Periodic Benefit Cost	1,038	955	2,076	1,819
Postretirement Benefits, U.S. Plans
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Interest cost	57	59	114	118
Amortization of Prior service cost (credit)	(58)	(62)	(116)	(124)
Net Periodic Benefit Cost	(1)	(3)	(2)	(6)
Postretirement Benefits, Non-U.S. Plans
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	284	281	568	562
Interest cost	222	221	444	442
Amortization of Net actuarial (gains) losses recognized	60	61	120	122
Net Periodic Benefit Cost	$ 566	$ 563	$ 1,132	$ 1,126