Earnings Per Share - Computation of EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Aug. 31, 2021	Aug. 31, 2020
Basic earnings per share:
Net income	$ 331,179	$ 300,005
Less: income allocated to participating securities	1,765	2,173
Income available to common shareholders	$ 329,414	$ 297,832
Basic weighted average common shares outstanding (in shares)	103,295	104,110
Basic earnings per share (in dollars per share)	$ 3.19	$ 2.86
Diluted earnings per share:
Net income	$ 331,179	$ 300,005
Less: income allocated to participating securities	1,765	2,173
Income available to common shareholders	$ 329,414	$ 297,832
Basic weighted average common shares outstanding (in shares)	103,295	104,110
Effect of dilutive securities - employee stock options (in shares)	2,649	3,019
Diluted weighted average common shares outstanding (in shares)	105,944	107,129
Diluted earnings per share (in dollars per share)	$ 3.11	$ 2.78