Income Taxes - Reconciliation from United States Statutory Federal Income Tax Rate to Effective Income Tax Rate (Detail)	12 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2016
Income Tax Disclosure [Abstract]
Federal income tax rate	29.20%	35.00%	35.00%
State taxes, net of federal benefit	1.20%	1.10%	1.10%
Foreign earnings	(18.40%)	(20.70%)	(18.20%)
Transition tax related to the Tax Act	43.30%		0.00%
Remeasurement of deferred tax assets and liabilities related to the Tax Act	3.70%		0.00%
Excess tax benefits from share-based compensation	(5.30%)		0.00%
Resolution of a U.S. tax matter	0.00%	(3.20%)	0.00%
Other, net	1.60%	1.00%	0.80%
EFFECTIVE INCOME TAX RATE	55.30%	13.20%	18.70%