Share-Based Activity under 2003 Plan (Detail) - Directors Equity Incentive Plan 2003 - $ / shares shares in Thousands	12 Months Ended
	May 31, 2020	May 31, 2019	May 31, 2018
Weighted Average Grant-Date Fair Value
Beginning balance	$ 54.56
Shares granted to Directors	67.26	$ 60.50	$ 51.63
Shares vested	50.61
Ending balance	$ 60.25	$ 54.56
Shares
Beginning balance	55
Shares granted to directors	23
Shares vested	(16)
Ending balance	62	55