Computation of Earnings Per Share - Schedule of Basic and Diluted Earnings per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended		6 Months Ended
		Nov. 30, 2017	Nov. 30, 2016	Nov. 30, 2017	Nov. 30, 2016
Basic earnings per common share:
Net earnings allocable to common shares	[1]	$ 774	$ 700	$ 1,369	$ 1,414
Weighted-average common shares		268.0	266.0	268.0	266.0
Basic earnings per common share		$ 2.89	$ 2.63	$ 5.12	$ 5.32
Diluted earnings per common share:
Net earnings allocable to common shares	[1]	$ 774	$ 700	$ 1,369	$ 1,414
Weighted-average common shares		268.0	266.0	268.0	266.0
Dilutive effect of share-based awards		4.0	4.0	4.0	4.0
Weighted-average diluted shares		272.0	270.0	272.0	270.0
Diluted earnings per common share		$ 2.84	$ 2.59	$ 5.03	$ 5.24
Anti-dilutive options excluded from diluted earnings per common share		2.9	5.1	3.0	5.1

[1] Net earnings available to participating securities were immaterial in all periods presented.