Retirement-Related Benefit Plans' Impact on Income Before Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Nov. 30, 2015	Nov. 30, 2014	Nov. 30, 2015	Nov. 30, 2014
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 9,600		$ 19,200
Interest cost	6,100		12,200
Pension Benefits, U.S. Plans
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	8,202	$ 7,564	16,404	$ 15,128
Interest cost	4,499	5,002	8,998	10,004
Expected return on plan assets	(6,437)	(6,034)	(12,874)	(12,068)
Prior service cost (credit)	58	74	116	148
Net actuarial (gains) losses recognized	4,190	3,472	8,380	6,944
Net Periodic Benefit Cost	10,512	10,078	21,024	20,156
Pension Benefits, Non-U.S. Plans
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	1,067	1,231	2,134	2,462
Interest cost	1,323	1,891	2,646	3,782
Expected return on plan assets	(1,983)	(2,296)	(3,966)	(4,592)
Prior service cost (credit)		10		20
Net actuarial (gains) losses recognized	457	536	914	1,072
Settlement	91		91
Net Periodic Benefit Cost	955	1,372	1,819	2,744
Postretirement Benefits, U.S. Plans
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Interest cost	59	66	118	132
Prior service cost (credit)	(62)	(62)	(124)	(124)
Net actuarial (gains) losses recognized		(34)		(68)
Net Periodic Benefit Cost	(3)	(30)	(6)	(60)
Postretirement Benefits, Non-U.S. Plans
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	281	313	562	626
Interest cost	221	308	442	616
Net actuarial (gains) losses recognized	61	104	122	208
Net Periodic Benefit Cost	$ 563	$ 725	$ 1,126	$ 1,450