Earnings Per Share - Computation of EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Nov. 30, 2019	Nov. 30, 2018	Nov. 30, 2019	Nov. 30, 2018
Basic Earnings per Share from Continuing Operations
Income from continuing operations	$ 246,443	$ 242,994	$ 497,255	$ 455,541
Less: income from continuing operations allocated to participating securities	2,425	3,376	4,904	6,308
Income from continuing operations available to common shareholders	$ 244,018	$ 239,618	$ 492,351	$ 449,233
Basic weighted average common shares outstanding (in shares)	103,959	106,475	103,638	106,652
Basic earnings per share from continuing operations (in dollars per share)	$ 2.35	$ 2.25	$ 4.75	$ 4.21
Diluted Earnings per Share from Continuing Operations
Income from continuing operations	$ 246,443	$ 242,994	$ 497,255	$ 455,541
Less: income from continuing operations allocated to participating securities	2,425	3,376	4,904	6,308
Income from continuing operations available to common shareholders	$ 244,018	$ 239,618	$ 492,351	$ 449,233
Basic weighted average common shares outstanding (in shares)	103,959	106,475	103,638	106,652
Effect of dilutive securities - employee stock options (in shares)	3,376	3,399	3,476	3,605
Diluted weighted average common shares outstanding (in shares)	107,335	109,874	107,114	110,257
Diluted earnings per share from continuing operations (in dollars per share)	$ 2.27	$ 2.18	$ 4.60	$ 4.07