Awards and Restricted Stock Units Issued under 2007 Plan and 2014 Omnibus Plan (Detail) - 2007 Plan and 2014 Omnibus Plan - $ / shares	12 Months Ended
	May 31, 2020	May 31, 2019	May 31, 2018
Weighted-Average Grant-Date Fair Value
Beginning Balance	$ 31.73
Shares granted	62.17	$ 60.01	$ 55.19
Shares exercised	33.96
Ending Balance	$ 33.82	$ 31.73
Shares
Beginning Balance	432,000
Shares granted	30,185
Shares exercised	(16,000)
Ending Balance	446,000	432,000