Earnings Per Share - Computation of EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Nov. 30, 2021	Nov. 30, 2020	Nov. 30, 2021	Nov. 30, 2020
Basic earnings per share:
Net income	$ 294,669	$ 284,857	$ 625,848	$ 584,862
Less: income allocated to participating securities	1,495	2,015	3,179	4,153
Income available to common shareholders	$ 293,174	$ 282,842	$ 622,669	$ 580,709
Basic weighted average common shares outstanding (in shares)	103,646	104,999	103,463	104,546
Basic earnings per share (in dollars per share)	$ 2.83	$ 2.69	$ 6.02	$ 5.55
Diluted earnings per share:
Net income	$ 294,669	$ 284,857	$ 625,848	$ 584,862
Less: income allocated to participating securities	1,495	2,015	3,179	4,153
Income available to common shareholders	$ 293,174	$ 282,842	$ 622,669	$ 580,709
Basic weighted average common shares outstanding (in shares)	103,646	104,999	103,463	104,546
Effect of dilutive securities - employee stock options (in shares)	2,476	2,982	2,563	3,010
Diluted weighted average common shares outstanding (in shares)	106,122	107,981	106,026	107,556
Diluted earnings per share (in dollars per share)	$ 2.76	$ 2.62	$ 5.87	$ 5.40