Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Feb. 28, 2019	Feb. 28, 2018	Feb. 28, 2019	Feb. 28, 2018
Basic Earnings per Share from Continuing Operations
Income from continuing operations	$ 200,923	$ 295,789	$ 656,464	$ 594,634
Less: income from continuing operations allocated to participating securities	2,783	5,248	8,977	10,546
Income from continuing operations available to common shareholders	$ 198,140	$ 290,541	$ 647,487	$ 584,088
Basic weighted average common shares outstanding (in shares)	105,080	106,558	106,147	106,210
Basic earnings per share from continuing operations (in dollars per share)	$ 1.89	$ 2.73	$ 6.10	$ 5.50
Diluted Earnings per Share from Continuing Operations
Income from continuing operations	$ 200,923	$ 295,789	$ 656,464	$ 594,634
Less: income from continuing operations allocated to participating securities	2,783	5,248	8,977	10,546
Income from continuing operations available to common shareholders	$ 198,140	$ 290,541	$ 647,487	$ 584,088
Basic weighted average common shares outstanding (in shares)	105,080	106,558	106,147	106,210
Effect of dilutive securities - employee stock options (in shares)	3,082	3,617	3,436	3,044
Diluted weighted average common shares outstanding (in shares)	108,162	110,175	109,583	109,254
Diluted earnings per share from continuing operations (in dollars per share)	$ 1.83	$ 2.66	$ 5.91	$ 5.35