Supplemental Cash Flow Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2016
Accounting Policies [Abstract]
Interest paid, net of amount capitalized	$ 34,839	$ 29,826	$ 30,431
Income taxes paid, net of refunds	$ 44,819	$ 55,652	$ 50,750